126
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Mohry TF, Maciołek A, Dietrich S. Structure and aggregation of colloids immersed in critical solvents. J Chem Phys 2012; 136:224903. [DOI: 10.1063/1.4722884] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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127
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Bernardino NR, Dietrich S. Complete wetting of elastically responsive substrates. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:051603. [PMID: 23004772 DOI: 10.1103/physreve.85.051603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 05/08/2012] [Indexed: 06/01/2023]
Abstract
We analyze theoretically complete wetting of a substrate supporting an array of parallel, vertical plates which can tilt elastically. The adsorbed liquid tilts the plates, inducing clustering, and thus modifies the substrate geometry. In turn, this change in geometry alters the wetting properties of the substrate and, consequently, the adsorption of liquid. This geometry-wetting feedback loop leads to stepped adsorption isotherms with each step corresponding to an abrupt change in the substrate geometry. We discuss how this can be used for constructing substrates with tunable wetting and adsorption properties.
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128
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Oeder S, Dietrich S, Weichenmeier I, Schober W, Pusch G, Jörres RA, Schierl R, Nowak D, Fromme H, Behrendt H, Buters JTM. Toxicity and elemental composition of particulate matter from outdoor and indoor air of elementary schools in Munich, Germany. INDOOR AIR 2012; 22:148-58. [PMID: 21913995 DOI: 10.1111/j.1600-0668.2011.00743.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
UNLABELLED Outdoor particulate matter (PM(10)) is associated with detrimental health effects. However, individual PM(10) exposure occurs mostly indoors. We therefore compared the toxic effects of classroom, outdoor, and residential PM(10). Indoor and outdoor PM(10) was collected from six schools in Munich during teaching hours and in six homes. Particles were analyzed by scanning electron microscopy and X-ray spectroscopy (EDX). Toxicity was evaluated in human primary keratinocytes, lung epithelial cells and after metabolic activation by several human cytochromes P450. We found that PM(10) concentrations during teaching hours were 5.6-times higher than outdoors (117 ± 48 μg/m(3) vs. 21 ± 15 μg/m(3), P < 0.001). Compared to outdoors, indoor PM contained more silicate (36% of particle number), organic (29%, probably originating from human skin), and Ca-carbonate particles (12%, probably originating from paper). Outdoor PM contained more Ca-sulfate particles (38%). Indoor PM at 6 μg/cm(2) (10 μg/ml) caused toxicity in keratinocytes and in cells expressing CYP2B6 and CYP3A4. Toxicity by CYP2B6 was abolished with the reactive oxygen species scavenger N-acetylcysteine. We concluded that outdoor PM(10) and indoor PM(10) from homes were devoid of toxicity. Indoor PM(10) was elevated, chemically different and toxicologically more active than outdoor PM(10). Whether the effects translate into a significant health risk needs to be determined. Until then, we suggest better ventilation as a sensible option. PRACTICAL IMPLICATIONS Indoor air PM(10) on an equal weight base is toxicologically more active than outdoor PM(10). In addition, indoor PM(10) concentrations are about six times higher than outdoor air. Thus, ventilation of classrooms with outdoor air will improve air quality and is likely to provide a health benefit. It is also easier than cleaning PM(10) from indoor air, which has proven to be tedious.
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129
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Dutka F, Napiórkowski M, Dietrich S. Mesoscopic analysis of Gibbs’ criterion for sessile nanodroplets on trapezoidal substrates. J Chem Phys 2012; 136:064702. [DOI: 10.1063/1.3682775] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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130
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Rousseaux J, Duhame A, Molnar D, Salleron J, Artero E, De Henauw S, Dietrich S, Kersting M, Manios Y, Piccinelli R, Sjöström M, Beghin L, Moreno L, Gottrand F. Pas d’influence de l’allaitement sur l’adiposité après la puberté : l’étude HELENA. Arch Pediatr 2011. [DOI: 10.1016/j.arcped.2011.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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131
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Bleibel J, Domínguez A, Oettel M, Dietrich S. Collective dynamics of colloids at fluid interfaces. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:125. [PMID: 22113398 DOI: 10.1140/epje/i2011-11125-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 10/26/2011] [Indexed: 05/31/2023]
Abstract
The evolution of an initially prepared distribution of micron-sized colloidal particles, trapped at a fluid interface and under the action of their mutual capillary attraction, is analyzed by using Brownian dynamics simulations. At a separation λ given by the capillary length of typically 1mm, the distance dependence of this attraction exhibits a crossover from a logarithmic decay, formally analogous to two-dimensional gravity, to an exponential decay. We discuss in detail the adaptation of a particle-mesh algorithm, as used in cosmological simulations to study structure formation due to gravitational collapse, to the present colloidal problem. These simulations confirm the predictions, as far as available, of a mean-field theory developed previously for this problem. The evolution is monitored by quantitative characteristics which are particularly sensitive to the formation of highly inhomogeneous structures. Upon increasing λ the dynamics shows a smooth transition from the spinodal decomposition expected for a simple fluid with short-ranged attraction to the self-gravitational collapse scenario.
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132
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Pinn-Bingham M, Zhang J, Dietrich S, Braggins W, Sehgal V, Al-Ghazi M, Wong J, Kuo J, Ramsinghani N. Dosimetric Parameters and Clinical Characteristics of Early Stage Breast Cancer Patients Treated with the SAVI Breast Brachytherapy Device. Int J Radiat Oncol Biol Phys 2011. [DOI: 10.1016/j.ijrobp.2011.06.462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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133
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Vasilyev O, Maciołek A, Dietrich S. Critical Casimir forces for Ising films with variable boundary fields. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:041605. [PMID: 22181149 DOI: 10.1103/physreve.84.041605] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Indexed: 05/31/2023]
Abstract
Monte Carlo simulations based on an integration scheme for free energy differences is used to compute critical Casimir forces for three-dimensional Ising films with various boundary fields. We study the scaling behavior of the critical Casimir force, including the scaling variable related to the boundary fields. Finite size corrections to scaling are taken into account. We pay special attention to that range of surface field strengths within which the force changes from repulsive to attractive upon increasing the temperature. Our data are compared with other results available in the literature.
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134
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Bleibel J, Dietrich S, Domínguez A, Oettel M. Shock waves in capillary collapse of colloids: a model system for two-dimensional screened Newtonian gravity. PHYSICAL REVIEW LETTERS 2011; 107:128302. [PMID: 22026805 DOI: 10.1103/physrevlett.107.128302] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Indexed: 05/31/2023]
Abstract
Using Brownian dynamics simulations, density functional theory, and analytical perturbation theory we study the collapse of a patch of interfacially trapped, micrometer-sized colloidal particles, driven by long-ranged capillary attraction. This attraction is formally analogous to two-dimensional (2D) screened Newtonian gravity with the capillary length λ as the screening length. Whereas the limit λ→∞ corresponds to the global collapse of a self-gravitating fluid, for finite λ[over ^] we predict theoretically and observe in simulations a ringlike density peak at the outer rim of a disclike patch, moving as an inbound shock wave. Possible experimental realizations are discussed.
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135
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Guzowski J, Tasinkevych M, Dietrich S. Capillary interactions in Pickering emulsions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:031401. [PMID: 22060365 DOI: 10.1103/physreve.84.031401] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 06/19/2011] [Indexed: 05/21/2023]
Abstract
The effective capillary interaction potentials for small colloidal particles trapped at the surface of liquid droplets are calculated analytically. Pair potentials between capillary monopoles and dipoles, corresponding to particles floating on a droplet with a fixed center of mass and subjected to external forces and torques, respectively, exhibit a repulsion at large angular separations and an attraction at smaller separations, with the latter resembling the typical behavior for flat interfaces. This change of character is not observed for quadrupoles, corresponding to free particles on a mechanically isolated droplet. The analytical results are compared with the numerical minimization of the surface free energy of the droplet in the presence of spherical or ellipsoidal particles.
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136
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Szalai I, Dietrich S. Magnetization of multicomponent ferrofluids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:326004. [PMID: 21795777 DOI: 10.1088/0953-8984/23/32/326004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The solution of the mean spherical approximation (MSA) integral equation for isotropic multicomponent dipolar hard sphere fluids without external fields is used to construct a density functional theory (DFT), which includes external fields, in order to obtain an analytical expression for the external field dependence of the magnetization of ferrofluidic mixtures. This DFT is based on a second-order Taylor series expansion of the free energy density functional of the anisotropic system around the corresponding isotropic MSA reference system. The ensuing results for the magnetic properties are in quantitative agreement with our canonical ensemble Monte Carlo simulation data presented here.
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137
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Sehgal V, Zhang J, Dietrich S, Al-Ghazi M, Wong J, Kuo J, Ramsinghani N. SU-E-T-381: Dosimetric Analysis of Patients Treated with Accelerated Partial Breast Irradiation Using the Mammosite® and SAVI Applicators. Med Phys 2011. [DOI: 10.1118/1.3612335] [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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138
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Schmitt T, Kasper B, Bischof M, Lehner B, Dietrich S, Dimitrakopoulou-Strauss A, Strauss LG, Mechtersheimer G, Wuchter P, Ho AD, Egerer G. A phase II trial evaluating efficacy of neo-/adjuvant EIA CTX, surgery, and radiation therapy in high-risk soft tissue sarcoma. J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.15_suppl.10076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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139
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Guzowski J, Tasinkevych M, Dietrich S. Free energy of colloidal particles at the surface of sessile drops. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 33:219-242. [PMID: 21072554 DOI: 10.1140/epje/i2010-10667-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 10/11/2010] [Indexed: 05/30/2023]
Abstract
The influence of finite system size on the free energy of a spherical particle floating at the surface of a sessile droplet is studied both analytically and numerically. In the special case that the contact angle at the substrate equals π/2 , a capillary analogue of the method of images is applied in order to calculate small deformations of the droplet shape if an external force is applied to the particle. The type of boundary conditions for the droplet shape at the substrate determines the sign of the capillary monopole associated with the image particle. Therefore, the free energy of the particle, which is proportional to the interaction energy of the original particle with its image, can be of either sign, too. The analytic solutions, given by the Green's function of the capillary equation, are constructed such that the condition of the forces acting on the droplet being balanced and of the volume constraint are fulfilled. Besides the known phenomena of attraction of a particle to a free contact line and repulsion from a pinned one, we observe a local free-energy minimum for the particle being located at the drop apex or at an intermediate angle, respectively. This peculiarity can be traced back to a non-monotonic behavior of the Green's function, which reflects the interplay between the deformations of the droplet shape and the volume constraint.
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140
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Gambassi A, Dietrich S. Colloidal aggregation and critical Casimir forces. PHYSICAL REVIEW LETTERS 2010; 105:059601-059602. [PMID: 20867957 DOI: 10.1103/physrevlett.105.059601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Indexed: 05/29/2023]
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141
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Domínguez A, Oettel M, Dietrich S. Dynamics of colloidal particles with capillary interactions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:011402. [PMID: 20866615 DOI: 10.1103/physreve.82.011402] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 06/14/2010] [Indexed: 05/29/2023]
Abstract
We investigate the dynamics of colloids at a fluid interface driven by attractive capillary interactions. At submillimeter length scales, the capillary attraction is formally analogous to two-dimensional gravity. In particular it is a nonintegrable interaction and it can be actually relevant for collective phenomena in spite of its weakness at the level of the pair potential. We introduce a mean-field model for the dynamical evolution of the particle number density at the interface. For generic values of the physical parameters the homogeneous distribution is found to be unstable against large-scale clustering driven by the capillary attraction. We also show that for the instability to be observable, the appropriate values for the relevant parameters (colloid radius, surface charge, external electric field, etc.) are experimentally well accessible. Our analysis contributes to current studies of the structure and dynamics of systems governed by long-ranged interactions and points toward their experimental realizations via colloidal suspensions.
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142
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Zhang J, Vanderbeck G, Dietrich S, Schiffner D, Wong J, Kuo J, Ramsinghani N, Al-Ghazi M, Roa D. SU-GG-T-109: Comprehensive RapidArc™ Treatment Planning and Quality Assurance for Head and Neck Cancers. Med Phys 2010. [DOI: 10.1118/1.3468498] [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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143
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Mohry TF, Maciołek A, Dietrich S. Crossover of critical Casimir forces between different surface universality classes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:061117. [PMID: 20866388 DOI: 10.1103/physreve.81.061117] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Indexed: 05/29/2023]
Abstract
In confined systems near a continuous phase transition the long-ranged fluctuations of the corresponding order parameter are subject to boundary conditions. These constraints result in so-called critical Casimir forces acting as effective forces on the confining surfaces. For systems belonging to the Ising bulk universality class corresponding to a scalar order parameter the critical Casimir force is studied for the film geometry in the crossover regime characterized by different surface fields at the two surfaces. The scaling function of the critical Casimir force is calculated within mean-field theory. Within our approach, the scaling functions of the critical Casimir force and of the order parameter profile for finite surface fields can be mapped by rescaling, except for a narrow crossover regime, onto the corresponding scaling function of the so-called normal fixed point of strong surface fields. In the crossover regime, the critical Casimir force as function of temperature exhibits more than one extremum and for certain ranges of surface field strengths it changes sign twice upon varying temperature. Monte Carlo simulation data obtained for a three-dimensional Ising film show similar trends. The sign of the critical Casimir force can be inferred from the comparison of the order parameter profiles in the film and in the semi-infinite geometry.
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144
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145
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Bernardino NR, Blickle V, Dietrich S. Wetting of surfaces covered by elastic hairs. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:7233-41. [PMID: 20112926 DOI: 10.1021/la904345r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We study the wetting properties of elastic hairy surfaces. Neither our theory nor our experiments support the suggestion by Otten and Herminghaus [Langmuir 2004, 20, 2405-2408] that the interplay between wetting, capillary interactions, and elasticity is responsible for the hydrophobic behavior of the leaves of a Lady's Mantle. Instead, the corresponding observations can be attributed to pinning of the contact line.
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146
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147
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148
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149
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Popescu MN, Dietrich S, Tasinkevych M, Ralston J. Phoretic motion of spheroidal particles due to self-generated solute gradients. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 31:351-367. [PMID: 20422245 DOI: 10.1140/epje/i2010-10593-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2010] [Accepted: 03/10/2010] [Indexed: 05/29/2023]
Abstract
We study theoretically the phoretic motion of a spheroidal particle, which generates solute gradients in the surrounding unbounded solvent via chemical reactions active on its surface in a cap-like region centered at one of the poles of the particle. We derive, within the constraints of the mapping to classical diffusio-phoresis, an analytical expression for the phoretic velocity of such an object. This allows us to analyze in detail the dependence of the velocity on the aspect ratio of the polar and the equatorial diameters of the particle and on the fraction of the particle surface contributing to the chemical reaction. The particular cases of a sphere and of an approximation for a needle-like particle, which are the most common shapes employed in experimental realizations of such self-propelled objects, are obtained from the general solution in the limits that the aspect ratio approaches one or becomes very large, respectively.
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150
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Hofmann T, Tasinkevych M, Checco A, Dobisz E, Dietrich S, Ocko BM. Wetting of nanopatterned grooved surfaces. PHYSICAL REVIEW LETTERS 2010; 104:106102. [PMID: 20366438 DOI: 10.1103/physrevlett.104.106102] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Indexed: 05/29/2023]
Abstract
The wetting by perfluoromethylcyclohexane of a well-defined silicon grating with a channel width of 16 nm has been studied using transmission small angle x-ray scattering. Prefilling, capillary filling, and postfilling wetting regimes have been identified. A detailed comparison of the data with theory reveals the importance of long-ranged substrate-fluid and fluid-fluid interactions for determining the wetting behavior on these length scales, especially at the onset of capillary condensation and in the prefilling regime.
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