Description of Micellar Radii for Phase Behavior and Viscosity Modeling of Aqueous Surfactant Solutions and Microemulsions.

The study of surfactant solutions and microemulsions is relevant for many industrial applications that include oil recovery, environmental remediation, and detergency. Understanding the coupled nature of microstructure, phase behavior, and rheology can help in the design of these applications. The microstructure of surfactant solutions and microemulsions determines their equilibrium properties, including phase composition and viscosity. Modeling microemulsion phase behavior by explicitly defining the shape and size of micelles allows for the consistent estimation of phase viscosity. We define a coupled microstructure-phase behavior-viscosity model by considering a two-dimensional lattice, where micelles are assumed to be elliptical. We also define equivalent three-dimensional models, where micelles are assumed to be oblate and prolate spheroids. The compositional dependence of the micellar radii is defined such that the oil-internal-bicontinuous-water-internal structural transitions are consistent with experimental observations. The model offers physical insights by modeling the transition between oil-internal-bicontinuous-water-internal regions in ternary diagrams as critical events, which are then tied to the unusual behavior observed in viscosity and scattering.

Coupled Interfacial Tension and Phase Behavior Model Based on Micellar Curvatures.

This article introduces a consistent and robust model that predicts interfacial tensions for all microemulsion Winsor types and overall compositions. The model incorporates film bending arguments and Huh's equation and is coupled to phase behavior so that simultaneous tuning of both interfacial tension (IFT) and phase behavior is possible. The oil-water interfacial tension and characteristic length are shown to be related to each other through the hydrophilic-lipophilic deviation (HLD). The phase behavior is tied to the micelle curvatures, without the need for using the net average curvature (NAC). The interfacial tension model is related to solubilization ratios in order to introduce a coupled interfacial tension-phase behavior model for all phase environments. The approach predicts two- and three-phase interfacial tensions and phase behavior (i.e., tie lines and tie triangles) for changes in composition and HLD input parameters, such as temperature, pressure, surfactant structure, and oil equivalent alkane carbon number. Comparisons to experimental data show excellent fits and predictive capability.

Automatic intraductal breast carcinoma classification using a neural network-based recognition system.

A contour-based automatic recognition system was applied to classify intraductal breast carcinoma into high nuclear grade and low nuclear grade in a digitized histologic image. The image discriminating characteristics were selected by their invariability condition to rotation and translation. They were acquired from cellular contours information. The totally interconnected multilayer perceptron network architecture was selected, and it was trained with the error back propagation algorithm. Forty cases were analyzed by the system and the diagnoses were compared with that of pathologist consensus, obtaining agreement in 97.5% (p < .00001 of cases). The system may become a very useful tool for the pathologist in the definitive classification of intraductal carcinoma.

The effect of preoperative bile salt administration on postoperative renal function in patients with obstructive jaundice.

We have studied the effect of the preoperative administration of bile salts on postoperative renal function in jaundiced patients undergoing surgery. Nine patients did not receive bile salts and in this group there were 2 cases of acute renal failure in the postoperative period. Furthermore, creatinine clearance values fell in this group from a mean value of 85 ml/min preoperatively to a mean postoperative value of 55 ml/min. Nine patients received preoperative bile salts with no case of renal failure. Creatinine clearance values increased in all but 2 patients from a mean preoperative value for the group 79 ml/min to a mean postoperative value for the group of 99 ml/min. The difference between the changes in creatinine clearance in the two groups was statistically significant (P less than 0.01). The results of this study suggest that the oral administration of bile salts to jaundiced patients in the preoperative period prevents deterioration in renal function postoperatively and also reduces the incidence of postoperative renal failure.