Curvature Dependence of Surface Free Energy of Liquid Drops and Bubbles: A Simulation Study

We study the excess free energy due to phase coexistence of fluids by Monte Carlo simulations using successive umbrella sampling in finite LxLxL boxes with periodic boundary conditions. Both the vapor-liquid phase coexistence of a simple Lennard-Jones fluid and the coexistence between A-rich and B-rich phases of a symmetric binary (AB) Lennard-Jones mixture are studied, varying the density rho in the simple fluid or the relative concentration x_A of A in the binary mixture, respectively. The character of phase coexistence changes from a spherical droplet (or bubble) of the minority phase (near the coexistence curve) to a cylindrical droplet (or bubble) and finally (in the center of the miscibility gap) to a slab-like configuration of two parallel flat interfaces. Extending the analysis of M. Schrader, P. Virnau, and K. Binder [Phys. Rev. E 79, 061104 (2009)], we extract the surface free energy gamma (R) of both spherical and cylindrical droplets and bubbles in the vapor-liquid case, and present evidence that for R -> Infinity the leading order (Tolman) correction for droplets has sign opposite to the case of bubbles, consistent with the Tolman length being independent on the sign of curvature. For the symmetric binary mixture the expected non-existence of the Tolman length is confirmed. In all cases {and for a range of radii} R relevant for nucleation theory, gamma(R) deviates strongly from gamma (Infinity) which can be accounted for by a term of order gamma(Infinity)/gamma(R)-1 ~ 1/R^2. Our results for the simple Lennard-Jones fluid are also compared to results from density functional theory and we find qualitative agreement in the behavior of gamma(R) as well as in the sign and magnitude of the Tolman length.Comment: 25 pages, submitted to J. Chem. Phy

The Publicity of Monticello: A Private Home as Emblem and Means

This paper examines how the private home of Thomas Jefferson, Monticello, was, in fact, designed and constructed in many ways as a public building. By examining how Jefferson created the spaces that would have been visited by guests to Monticello, one can see that visitors were intended to have meaningful, affecting experiences at the home. I have broken down the study of these experiences into two parts: the first examines Monticello as a personal emblem of Jefferson’s aesthetic and political philosophy; the second explores Monticello as a means to crafting Jefferson\u27s personal vision of America. I argue that Jefferson intended his home to be both reflective and didactic, and as a result provide an analysis of how private spaces can be utilized to influence and engage with visitors to essentially create a smaller, public space within a larger private realm

Master of Science

thesisThe effects of varying electrode geometry (ball and ring) and size (radius), dielectric media (castor oil and Diala® oil), specimen thickness, and concentration of defects on the dielectric breakdown strength of commercial-grade alumina and high-purity fine-grained (HPFG) alumina were investigated. The breakdown strength was expressed in terms of the maximum electric field in the ceramic at the breakdown voltage calculated by finite element analysis (FEA). The breakdown strength decreased systematically with increasing electrode radius and specimen thickness. The breakdown strength increased with decreasing concentration of defects. The breakdown strength was higher in the Diala® oil (dielectric constant, £r = 2.3 ± 0.12) as compared to the castor oil (£r = 4.59 ± 0.06). The breakdown strength was higher for the HPFG alumina as compared to the commercial-grade alumina. These effects of the electrode geometry, specimen thickness, concentration of defects, and of the dielectric media were analyzed with a weakest-link failure model employing the Laplace and Weibull distributions for a population of defects in the material. The measured size or scaling effects of the electrodes, specimen thickness, concentration of defects, and of the liquid media on breakdown strength were in better agreement with the Laplace distribution for the population. The measured concentration of surface defects was in good agreement with the concentration of surface defects estimated from the surface area scaling of the breakdown field with the Laplace distribution

Secret Signals from Another World: Walter Benjamin’s Concept of Innervation

Walter Benjamin refers to the “idea of revolution as an innervation of the technical organs of the collective” as one of the articles of his politics. The significance of this assertion has received relatively little attention in the philosophical reception of his political thought compared to the alternative model of revolution – made famous from the paralipomena to the late theses ‘On the Concept of History’ – as the emergency handbrake of history. Drawing on some of the debates and tensions generated by the work of Miriam Bratu Hansen, this discussion aims at an exegesis of some of the lesser known intellectual sources that influenced Benjamin’s theory of innervation. The purpose in doing so is not an attempt to reconcile or integrate these sources with dominant philosophical reconstructions of what is sometimes characterized as Benjamin’s “Western Marxism” and elaborated, in the more familiar context of Surrealist innervation, as a synthesis of Freud and Marx, but rather to reveal an alternative constellation of Soviet biomechanics and reactionary anti-capitalist Lebensphilosophie, united in their shared rejection of Freudian psychoanalysis

Monte Carlo Methods for Estimating Interfacial Free Energies and Line Tensions

Excess contributions to the free energy due to interfaces occur for many problems encountered in the statistical physics of condensed matter when coexistence between different phases is possible (e.g. wetting phenomena, nucleation, crystal growth, etc.). This article reviews two methods to estimate both interfacial free energies and line tensions by Monte Carlo simulations of simple models, (e.g. the Ising model, a symmetrical binary Lennard-Jones fluid exhibiting a miscibility gap, and a simple Lennard-Jones fluid). One method is based on thermodynamic integration. This method is useful to study flat and inclined interfaces for Ising lattices, allowing also the estimation of line tensions of three-phase contact lines, when the interfaces meet walls (where "surface fields" may act). A generalization to off-lattice systems is described as well. The second method is based on the sampling of the order parameter distribution of the system throughout the two-phase coexistence region of the model. Both the interface free energies of flat interfaces and of (spherical or cylindrical) droplets (or bubbles) can be estimated, including also systems with walls, where sphere-cap shaped wall-attached droplets occur. The curvature-dependence of the interfacial free energy is discussed, and estimates for the line tensions are compared to results from the thermodynamic integration method. Basic limitations of all these methods are critically discussed, and an outlook on other approaches is given

Persons, Minds, and Bodies

Philosophyhttp://deepblue.lib.umich.edu/bitstream/2027.42/85309/1/jamblock.pd