51
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Dietrich S, Düring A, Rothkirch D, Filippopulos F, Eren O, Dresler T, Buchwald T, Straube A, Zierz S, Goßrau G, Kraya T. P 165 Incidence, clinical characteristics and longterm course of headache in patients with stroke (DMKG multicenter study). Clin Neurophysiol 2017. [DOI: 10.1016/j.clinph.2017.06.236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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52
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Labbé-Laurent M, Law AD, Dietrich S. Liquid bridging of cylindrical colloids in near-critical solvents. J Chem Phys 2017; 147:104701. [DOI: 10.1063/1.4986149] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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53
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Gross M, Gambassi A, Dietrich S. Statistical field theory with constraints: Application to critical Casimir forces in the canonical ensemble. Phys Rev E 2017; 96:022135. [PMID: 28950535 DOI: 10.1103/physreve.96.022135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Indexed: 06/07/2023]
Abstract
The effect of imposing a constraint on a fluctuating scalar order parameter field in a system of finite volume is studied within statistical field theory. The canonical ensemble, corresponding to a fixed total integrated order parameter (e.g., the total number of particles), is obtained as a special case of the theory. A perturbative expansion is developed which allows one to systematically determine the constraint-induced finite-volume corrections to the free energy and to correlation functions. In particular, we focus on the Landau-Ginzburg model in a film geometry (i.e., in a rectangular parallelepiped with a small aspect ratio) with periodic, Dirichlet, or Neumann boundary conditions in the transverse direction and periodic boundary conditions in the remaining, lateral directions. Within the expansion in terms of ε=4-d, where d is the spatial dimension of the bulk, the finite-size contribution to the free energy of the confined system and the associated critical Casimir force are calculated to leading order in ε and are compared to the corresponding expressions for an unconstrained (grand canonical) system. The constraint restricts the fluctuations within the system and it accordingly modifies the residual finite-size free energy. The resulting critical Casimir force is shown to depend on whether it is defined by assuming a fixed transverse area or a fixed total volume. In the former case, the constraint is typically found to significantly enhance the attractive character of the force as compared to the grand canonical case. In contrast to the grand canonical Casimir force, which, for supercritical temperatures, vanishes in the limit of thick films, in the canonical case with fixed transverse area the critical Casimir force attains for thick films a negative value for all boundary conditions studied here. Typically, the dependence of the critical Casimir force both on the temperaturelike and on the fieldlike scaling variables is different in the two ensembles.
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54
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Dietrich S, Oleś M, Sellner L, Anders S, Lu J, Velten B, Mock A, Oakes C, Sutton L, Young E, Rosenquist R, Rossi D, Zirlik K, Herling M, Nguyen-Khac F, Plass C, von Kalle C, Dürig J, Ringshausen I, Huber W, Zenz T. DRUG PERTURBATION BASED STRATIFICATION OF LYMPHOPROLIFERATIVE DISORDERS. Hematol Oncol 2017. [DOI: 10.1002/hon.2437_41] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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55
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Reindl A, Bier M, Dietrich S. Electrolyte solutions at curved electrodes. II. Microscopic approach. J Chem Phys 2017; 146:154704. [DOI: 10.1063/1.4979948] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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56
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Reindl A, Bier M, Dietrich S. Electrolyte solutions at curved electrodes. I. Mesoscopic approach. J Chem Phys 2017; 146:154703. [DOI: 10.1063/1.4979947] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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57
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Farahmand Bafi N, Maciołek A, Dietrich S. Tricritical Casimir forces and order parameter profiles in wetting films of ^{3}He-^{4}He mixtures. Phys Rev E 2017; 95:032802. [PMID: 28415225 DOI: 10.1103/physreve.95.032802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Indexed: 11/07/2022]
Abstract
Tricritical Casimir forces in ^{3}He-^{4}He wetting films are studied, within mean field theory, in terms of a suitable lattice gas model for binary liquid mixtures with short-ranged surface fields. The proposed model takes into account the continuous rotational symmetry O(2) of the superfluid degrees of freedom associated with ^{4}He and it allows, inter alia, for the occurrence of a vapor phase. As a result, the model facilitates the formation of wetting films, which provides a strengthened theoretical framework to describe available experimental data for tricritical Casimir forces acting in ^{3}He-^{4}He wetting films.
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58
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Popescu MN, Uspal WE, Dietrich S. Chemically active colloids near osmotic-responsive walls with surface-chemistry gradients. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:134001. [PMID: 28140364 DOI: 10.1088/1361-648x/aa5bf1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Chemically active colloids move by creating gradients in the composition of the surrounding solution and by exploiting the differences in their interactions with the various molecular species in solution. If such particles move near boundaries, e.g. the walls of the container confining the suspension, gradients in the composition of the solution are also created along the wall. This give rise to chemi-osmosis (via the interactions of the wall with the molecular species forming the solution), which drives flows coupling back to the colloid and thus influences its motility. Employing an approximate 'point-particle' analysis, we show analytically that-owing to this kind of induced active response (chemi-osmosis) of the wall-such chemically active colloids can align with, and follow, gradients in the surface chemistry of the wall. In this sense, these artificial 'swimmers' exhibit a primitive form of thigmotaxis with the meaning of sensing the proximity of a (not necessarily discontinuous) physical change in the environment. We show that the alignment with the surface-chemistry gradient is generic for chemically active colloids as long as they exhibit motility in an unbounded fluid, i.e. this phenomenon does not depend on the exact details of the propulsion mechanism. The results are discussed in the context of simple models of chemical activity, corresponding to Janus particles with 'source' chemical reactions on one half of the surface and either 'inert' or 'sink' reactions over the other half.
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59
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Popescu MN, Uspal WE, Tasinkevych M, Dietrich S. Perils of ad hoc approximations for the activity function of chemically powered colloids. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2017; 40:42. [PMID: 28389824 DOI: 10.1140/epje/i2017-11529-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/13/2017] [Indexed: 06/07/2023]
Abstract
Colloids can achieve motility by promoting at their surfaces chemical reactions in the surrounding solution. A well-studied case is that of self-phoresis, in which motility arises due to the spatial inhomogeneities in the chemical composition of the solution and the distinct interactions of the solvent molecules and of the reaction products with the colloid. For simple models of such chemically active colloids, the steady-state motion in an unbounded solution can be derived analytically in closed form. In contrast, for such chemically active particles moving in the vicinity of walls, the derivation of closed-form and physically intuitive solutions of the equations governing their dynamics turns out to be a severe challenge even for simple models. Therefore, recent studies of these phenomena have employed numerical methods as well as approximate analytical approaches based on multipolar expansions. We discuss and clarify certain conceptual aspects concerning the latter type of approach, which arise due to ad hoc truncations of the underlying so-called activity function, which describes the distribution of chemical reactions across the surface of the particle.
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60
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Domínguez A, Malgaretti P, Popescu MN, Dietrich S. Collective dynamics of chemically active particles trapped at a fluid interface. SOFT MATTER 2016; 12:8398-8406. [PMID: 27714377 DOI: 10.1039/c6sm01468b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Chemically active colloids generate changes in the chemical composition of their surrounding solution and thereby induce flows in the ambient fluid which affect their dynamical evolution. Here we study the many-body dynamics of a monolayer of spherically symmetric active particles trapped at a fluid-fluid interface. To this end we consider a model for the large-scale spatial distribution of particles which incorporates the direct pair interaction (including also the capillary interaction which is caused specifically by the interfacial trapping) as well as the effect of hydrodynamic interactions (including the Marangoni flow induced by the response of the interface to the chemical activity). The values of the relevant physical parameters for typical experimental realizations of such systems are estimated and various scenarios, which are predicted by our approach for the dynamics of the monolayer, are discussed. In particular, we show that the chemically-induced Marangoni flow can prevent the clustering instability driven by the capillary attraction.
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61
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Roy S, Dietrich S, Höfling F. Structure and dynamics of binary liquid mixtures near their continuous demixing transitions. J Chem Phys 2016; 145:134505. [DOI: 10.1063/1.4963771] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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62
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Bourgeois D, Seghal V, Dietrich S, Yu S, Kuo J, Ramsinghani N, Al-Ghazi M, Daroui P. Dosimetric Comparison of Deep Inspiration Breath Hold and Free Breathing Treatment Techniques for Left-sided Breast Cancer Using 3-Dimensional Surface Tracking. Int J Radiat Oncol Biol Phys 2016. [DOI: 10.1016/j.ijrobp.2016.06.682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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63
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Dietrich S, Düring A, Rothkirch D, Filippopulos F, Eren O, Dresler T, Straube A, Goßrau G, Kraya T. EP 9. Prevalence, clinical characteristics and long-term course of headache in patients with stroke (multicenter study of DMKG). Clin Neurophysiol 2016. [DOI: 10.1016/j.clinph.2016.05.064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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64
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Labbé-Laurent M, Dietrich S. Critical Casimir interactions between Janus particles. SOFT MATTER 2016; 12:6621-6648. [PMID: 27444691 DOI: 10.1039/c6sm00990e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recently there has been strong experimental and theoretical interest in studying the self-assembly and the phase behavior of patchy and Janus particles, which form colloidal suspensions. Although in this quest a variety of effective interactions have been proposed and used in order to achieve a directed assembly, the critical Casimir effect stands out as being particularly suitable in this respect because it provides both attractive and repulsive interactions as well as the potential of a sensitive temperature control of their strength. Specifically, we have calculated the critical Casimir force between a single Janus particle and a laterally homogeneous substrate as well as a substrate with a chemical step. We have used the Derjaguin approximation and compared it with results from full mean field theory. A modification of the Derjaguin approximation turns out to be generally reliable. Based on this approach we have derived the effective force and the effective potential between two Janus cylinders as well as between two Janus spheres.
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65
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Słabicki M, Lee KS, Jethwa A, Sellner L, Sacco F, Walther T, Hüllein J, Dietrich S, Wu B, Lipka DB, Oakes CC, Mamidi S, Pyrzyńska B, Winiarska M, Oleś M, Seifert M, Plass C, Kirschfink M, Boettcher M, Gołąb J, Huber W, Fröhling S, Zenz T. Dissection of CD20 regulation in lymphoma using RNAi. Leukemia 2016; 30:2409-2412. [PMID: 27560109 DOI: 10.1038/leu.2016.230] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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66
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Majee A, Bier M, Dietrich S. Poisson-Boltzmann study of the effective electrostatic interaction between colloids at an electrolyte interface. J Chem Phys 2016. [DOI: 10.1063/1.4960623] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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67
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Domínguez A, Malgaretti P, Popescu MN, Dietrich S. Erratum: Effective Interaction between Active Colloids and Fluid Interfaces Induced by Marangoni Flows [Phys. Rev. Lett. 116, 078301 (2016)]. PHYSICAL REVIEW LETTERS 2016; 117:079902. [PMID: 27564004 DOI: 10.1103/physrevlett.117.079902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Indexed: 06/06/2023]
Abstract
This corrects the article DOI: 10.1103/PhysRevLett.116.078301.
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68
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Gross M, Vasilyev O, Gambassi A, Dietrich S. Critical adsorption and critical Casimir forces in the canonical ensemble. Phys Rev E 2016; 94:022103. [PMID: 27627242 DOI: 10.1103/physreve.94.022103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Indexed: 06/06/2023]
Abstract
Critical properties of a liquid film between two planar walls are investigated in the canonical ensemble, within which the total number of fluid particles, rather than their chemical potential, is kept constant. The effect of this constraint is analyzed within mean-field theory (MFT) based on a Ginzburg-Landau free-energy functional as well as via Monte Carlo simulations of the three-dimensional Ising model with fixed total magnetization. Within MFT and for finite adsorption strengths at the walls, the thermodynamic properties of the film in the canonical ensemble can be mapped exactly onto a grand canonical ensemble in which the corresponding chemical potential plays the role of the Lagrange multiplier associated with the constraint. However, due to a nonintegrable divergence of the mean-field order parameter profile near a wall, the limit of infinitely strong adsorption turns out to be not well-defined within MFT, because it would necessarily violate the constraint. The critical Casimir force (CCF) acting on the two planar walls of the film is generally found to behave differently in the canonical and grand canonical ensembles. For instance, the canonical CCF in the presence of equal preferential adsorption at the two walls is found to have the opposite sign and a slower decay behavior as a function of the film thickness compared to its grand canonical counterpart. We derive the stress tensor in the canonical ensemble and find that it has the same expression as in the grand canonical case, but with the chemical potential playing the role of the Lagrange multiplier associated with the constraint. The different behavior of the CCF in the two ensembles is rationalized within MFT by showing that, for a prescribed value of the thermodynamic control parameter of the film, i.e., density or chemical potential, the film pressures are identical in the two ensembles, while the corresponding bulk pressures are not.
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69
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Uspal WE, Popescu MN, Dietrich S, Tasinkevych M. Guiding Catalytically Active Particles with Chemically Patterned Surfaces. PHYSICAL REVIEW LETTERS 2016; 117:048002. [PMID: 27494500 DOI: 10.1103/physrevlett.117.048002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Indexed: 06/06/2023]
Abstract
Catalytically active Janus particles suspended in solution create gradients in the chemical composition of the solution along their surfaces, as well as along any nearby container walls. The former leads to self-phoresis, while the latter gives rise to chemiosmosis, providing an additional contribution to self-motility. Chemiosmosis strongly depends on the molecular interactions between the diffusing chemical species and the wall. We show analytically, using an approximate "point-particle" approach, that by chemically patterning a planar substrate one can direct the motion of Janus particles: the induced chemiosmotic flows can cause particles to either "dock" at the chemical step between the two materials or follow a chemical stripe. These theoretical predictions are confirmed by full numerical calculations. Generically, docking occurs for particles which tend to move away from their catalytic caps, while stripe following occurs in the opposite case. Our analysis reveals the physical mechanisms governing this behavior.
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70
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Kobalz K, Kobalz M, Möllmer J, Junghans U, Lange M, Bergmann J, Dietrich S, Wecks M, Gläser R, Krautscheid H. Bis(carboxyphenyl)-1,2,4-triazole Based Metal–Organic Frameworks: Impact of Metal Ion Substitution on Adsorption Performance. Inorg Chem 2016; 55:6938-48. [DOI: 10.1021/acs.inorgchem.6b00530] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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71
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Ibagon I, Bier M, Dietrich S. Three-phase contact line and line tension of electrolyte solutions in contact with charged substrates. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:244015. [PMID: 27116050 DOI: 10.1088/0953-8984/28/24/244015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The three-phase contact line formed by the intersection of a liquid-vapor interface of an electrolyte solution with a charged planar substrate is studied in terms of classical density functional theory applied to a lattice model. The influence of the substrate charge density and of the ionic strength of the solution on the intrinsic structure of the three-phase contact line and on the corresponding line tension is analyzed. We find a negative line tension for all values of the surface charge density and of the ionic strength considered. The strength of the line tension decreases upon decreasing the contact angle via varying either the temperature or the substrate charge density.
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72
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Laoui S, Dietrich S, Sehgal V, Al-Ghazi M. SU-F-T-35: Optimization of Bladder and Rectal Doses Using a Multi-Lumen Intracavitary Applicator for Gynecological Brachytherapy. Med Phys 2016. [DOI: 10.1118/1.4956170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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73
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Sierra L, Cacciabue L, Dietrich S, Weinzettel P, Bea S. Arsenic in groundwater and sediments in a loessic aquifer, Argentina. ARSENIC IN THE ENVIRONMENT - PROCEEDINGS 2016. [DOI: 10.1201/b20466-45] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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74
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Malgaretti P, Popescu MN, Dietrich S. Active colloids at fluid interfaces. SOFT MATTER 2016; 12:4007-4023. [PMID: 27025167 DOI: 10.1039/c6sm00367b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
If an active Janus particle is trapped at the interface between a liquid and a fluid, its self-propelled motion along the interface is affected by a net torque on the particle due to the viscosity contrast between the two adjacent fluid phases. For a simple model of an active, spherical Janus colloid we analyze the conditions under which translation occurs along the interface and we provide estimates of the corresponding persistence length. We show that under certain conditions the persistence length of such a particle is significantly larger than the corresponding one in the bulk liquid, which is in line with the trends observed in recent experimental studies.
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75
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Domínguez A, Malgaretti P, Popescu MN, Dietrich S. Effective Interaction between Active Colloids and Fluid Interfaces Induced by Marangoni Flows. PHYSICAL REVIEW LETTERS 2016; 116:078301. [PMID: 26943561 DOI: 10.1103/physrevlett.116.078301] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Indexed: 05/10/2023]
Abstract
We show theoretically that near a fluid-fluid interface a single active colloidal particle generating, e.g., chemicals or a temperature gradient experiences an effective force of hydrodynamic origin. This force is due to the fluid flow driven by Marangoni stresses induced by the activity of the particle; it decays very slowly with the distance from the interface, and can be attractive or repulsive depending on how the activity modifies the surface tension. We show that, for typical systems, this interaction can dominate the dynamics of the particle as compared to Brownian motion, dispersion forces, or self-phoretic effects. In the attractive case, the interaction promotes the self-assembly of particles into a crystal-like monolayer at the interface.
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