RESUMEN
Thermo-osmotic flows, generated at liquid-solid interfaces by thermal gradients, can be used to produce electric currents from waste heat on charged surfaces. The two key parameters controlling the thermo-osmotic current are the surface charge and the interfacial enthalpy excess due to liquid-solid interactions. While it has been shown that the contribution from water to the enthalpy excess can be crucial, how this contribution is affected by surface charge remained to be understood. Here, we start by discussing how thermo-osmotic flows and induced electric currents are related to the interfacial enthalpy excess. We then use molecular dynamics simulations to investigate the impact of surface charge on the interfacial enthalpy excess, for different distributions of the surface charge, and two different wetting conditions. We observe that surface charge has a strong impact on enthalpy excess, and that the dependence of enthalpy excess on surface charge depends largely on its spatial distribution. In contrast, wetting has a very small impact on the charge-enthalpy coupling. We rationalize the results with simple analytical models, and explore their consequences for thermo-osmotic phenomena. Overall, this work provides guidelines to search for systems providing optimal waste heat recovery performance.
RESUMEN
Thermo-osmotic flows - flows generated in micro and nanofluidic systems by thermal gradients - could provide an alternative approach to harvest waste heat. However, such use would require massive thermo-osmotic flows, which are up to now only predicted for special and expensive materials. Thus, there is an urgent need to design affordable nanofluidic systems displaying large thermo-osmotic coefficients. In this paper, we propose a general model for thermo-osmosis of aqueous electrolytes in charged nanofluidic channels, taking into account hydrodynamic slip, together with the different solvent and solute contributions to the thermo-osmotic response. We apply this model to a wide range of systems by studying the effects of wetting, salt type and concentration, and surface charge. We show that intense thermo-osmotic flows can be generated using slipping charged surfaces. We also predict for intermediate wettings a transition from a thermophobic to a thermophilic behavior depending on the surface charge and salt concentration. Overall, this theoretical framework opens an avenue for controlling and manipulating thermally induced flows with common charged surfaces and a pinch of salt.
RESUMEN
Although several thousand patients are diagnosed with sarcoma annually in the United States, metastases to the heart are very uncommon. In this case report, an overall low frequency cancer presents masquerading with common cardiac symptomology. This case illustrates the importance for detailed diagnostic cardiac evaluations and heightened suspicion by physicians to consider metastatic disease to the heart in cancer patients with cardiovascular complications. Also discussed is a review of surgical and chemotherapeutic options for this problem.
RESUMEN
BACKGROUND: Capsular contracture remains one of the most common complications involving aesthetic and reconstructive breast surgery; however, its cause, prevention, and treatment remain to be fully elucidated. Presently, there is no accurate and reproducible pathologic in vitro or in vivo model examining capsular contracture. The purpose of this study was to establish an effective pathologic capsular contracture animal model that mimics the formation of capsular contracture response in humans. METHODS: New Zealand White rabbits (n = 32) were subdivided into experimental (n = 16) and control groups (n = 16). Each subgroup underwent placement of smooth saline mini implants (30 cc) beneath the panniculus carnosus in the dorsal region of the back. In addition, the experimental group underwent instillation of fibrin glue into the implant pocket as a capsular contracture-inducing agent. Rabbits were euthanized from 2 to 8 weeks after the procedure. Before the animals were euthanized, each implant was serially inflated with saline and a pressure-volume curve was developed using a Stryker device to assess the degree of contracture. Representative capsule samples were collected and histologically examined. Normal and contracted human capsular tissue samples were also collected from patients undergoing breast implant revision and replacement procedures. Tissue samples were assessed histologically. RESULTS: Pressure-volume curves demonstrated a statistically significantly increased intracapsular pressure in the experimental group compared with the control group. The experimental subgroup had thicker, less transparent capsules than the control group. Histologic evaluation of the rabbit capsule was similar to that of the human capsule for the control and experimental subgroups. CONCLUSIONS: The authors conclude that pathologic capsular contracture can be reliably induced in the rabbit. This animal model provides the framework for future investigations testing the effects of various systemic or local agents on reduction of capsular contracture.