Phase behavior of a binary mixture of patchy colloids: Effect of particle size and gravity.

We study theoretically the effect of size difference and that of gravity in the phase behavior of a binary mixture of patchy particles. The species, 2A and 3B, have two A and three B patches, respectively, and only bonds between patches A and B (AB bonds) are allowed. This model describes colloidal systems where the aggregation of particles (3B) is mediated and controlled by a second species, the linkers (2A) to which they bind strongly.

Free energy calculations for rings and chains formed by dipolar hard spheres.

We employ a method based on Monte Carlo grand-canonical simulations to precisely calculate partition functions of non-interacting chains and rings formed by dipolar hard spheres (DHS) at low temperature. The extended low temperature region offered by such cluster calculations, compared to what had been previously achieved with standard simulations, opens up the possibility of exploring a part of the DHS phase diagram which was inaccessible before. The reported results offer the unique opportunity of verifying well-established theoretical models based on the ideal gas of cluster approximation in order to clarify their range of validity.

Communication: Re-entrant limits of stability of the liquid phase and the Speedy scenario in colloidal model systems.

A re-entrant gas-liquid spinodal was proposed as a possible explanation of the apparent divergence of the compressibility and specific heat off supercooling water. Such a counter-intuitive possibility, e.g.

Temperature-induced structural transitions in self-assembling magnetic nanocolloids.

With the help of a unique combination of density functional theory and computer simulations, we discover two possible scenarios, depending on concentration, for the hierarchical self-assembly of magnetic nanoparticles on cooling. We show that typically considered low temperature clusters, i.e.

Self-assembly in chains, rings, and branches: a single component system with two critical points.

We study the interplay between phase separation and self-assembly in chains, rings, and branched structures in a model of particles with dissimilar patches. We extend Wertheim's first order perturbation theory to include the effects of ring formation and to theoretically investigate the thermodynamics of the model. We find a peculiar shape for the vapor-liquid coexistence, featuring reentrant behavior in both phases and two critical points, despite the single-component nature of the system.

Branching points in the low-temperature dipolar hard sphere fluid.

In this contribution, we investigate the low-temperature, low-density behaviour of dipolar hard-sphere (DHS) particles, i.e., hard spheres with dipoles embedded in their centre.

Computing the phase diagram of binary mixtures: a patchy particle case study.

We investigate the phase behaviour of 2D mixtures of bi-functional and three-functional patchy particles and 3D mixtures of bi-functional and tetra-functional patchy particles by means of Monte Carlo simulations and Wertheim theory. We start by computing the critical points of the pure systems and then we investigate how the critical parameters change upon lowering the temperature. We extend the successive umbrella sampling method to mixtures to make it possible to extract information about the phase behaviour of the system at a fixed temperature for the whole range of densities and compositions of interest.

Nonmonotonic magnetic susceptibility of dipolar hard-spheres at low temperature and density.

We investigate, via numerical simulations, mean field, and density functional theories, the magnetic response of a dipolar hard sphere fluid at low temperatures and densities, in the region of strong association. The proposed parameter-free theory is able to capture both the density and temperature dependence of the ring-chain equilibrium and the contribution to the susceptibility of a chain of generic length. The theory predicts a nonmonotonic temperature dependence of the initial (zero field) magnetic susceptibility, arising from the competition between magnetically inert particle rings and magnetically active chains.

Locally advanced penile carcinoma: classic emasculation or testis-sparing surgery?

Purpose: The study evaluates the clinical and pathological findings of 16 patients with locally advanced penile carcinoma (PC) submitted to emasculation, and discusses questions related to the usefulness of bilateral orchiectomy.

Materials And Methods: Between 1999 and 2010, 172 patients with PC were treated. Sixteen (9 %) underwent emasculation.

Properties of patchy colloidal particles close to a surface: a Monte Carlo and density functional study.

We investigate the behavior of a patchy particle model close to a hard-wall via Monte Carlo simulation and density functional theory (DFT). Two DFT approaches, based on the homogeneous and inhomogeneous versions of Wertheim's first order perturbation theory for the association free energy are used. We evaluate, by simulation and theory, the equilibrium bulk phase diagram of the fluid and analyze the surface properties for two isochores, one of which is close to the liquid side of the gas-liquid coexistence curve.

Quantitative description of the self-assembly of patchy particles into chains and rings.

We numerically study a simple fluid composed of particles having a hard-core repulsion complemented by two patchy attractive sites on the particle poles. An appropriate choice of the patch angular width allows for the formation of ring structures which, at low temperatures and low densities, compete with the growth of linear aggregates. The simplicity of the model makes it possible to compare simulation results and theoretical predictions based on the Wertheim perturbation theory, specialized to the case in which ring formation is allowed.

Phase diagrams of binary mixtures of patchy colloids with distinct numbers and types of patches: the empty fluid regime.

We investigate the effect of distinct bonding energies on the onset of criticality of low functionality fluid mixtures. We focus on mixtures of particles with two and three patches as this includes the mixture where "empty" fluids were originally reported. In addition to the number of patches, the species differ in the type of patches or bonding sites.

Extraperitoneal surgical repair of parastomal hernia of Bricker's urinary diversion with polypropylene mesh: stoma reimplantation through the mesh.

Introduction: Parastomal hernias affect 4.5-9% of patients submitted to ileostomy. Correcting this hernia represents a challenge.

Vaginal osseous metaplasia.

Background: Osseous metaplasia is an unusual event in the gynecologic organs. It has been reported mostly in the endometrium and rarely in the cervix.

Case: The authors describe a rare case of bone formation in vaginal mucosa of a 52-year-old woman with chronic pelvic pain and exteriorization of bone from vaginal introit.

The isolated gamma probe technique for sentinel node penile carcinoma detection is unreliable.

Purpose: Penile carcinoma is a common disease in northeast Brazil. This paper shows the results of the use of isolated gamma probe and discusses the incidence of false negative rates.

Materials And Methods: From July 2000 to September 2003, 27 newly diagnosed penile carcinoma patients (T1, T2, N0) were included in this prospective study.

Aggressive vaginal angiomyxoma mimicking urethral tumor.

This is a case report of a 32-year-old female patient with a neoplasia mimicking a urethral tumor. Following anterior pelvic exanteration, vulvectomy, bilateral inguinal lymphadenectomy, the pathological study established the diagnosis of aggressive vaginal angiomyxoma, CD-34 labeled.