Is Blue Dye Indicated for Sentinel Lymph Node Biopsy in Breast Cancer Patients With a Positive Lymphoscintigram?

The use of isosulfan blue dye in sentinel node biopsy for breast cancer has been questioned because of its risk of allergic reaction. We hypothesized that blue dye could be safely omitted in the subgroup of patients who have evidence of successful sentinel node localization by lymphoscintigraphy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41406/1/10434_2005_Article_6556.pd

Catastrophic Drop Breakup in Electric Field

We report novel observations revealing the catastrophic breakup of water drops containing surfactant molecules, which are suspended in oil and subjected to an electric field of strength similar to 10(5) V/m. The observed breakup was distinctly different from the gradual end pinch-off or tip-streaming modes reported earlier in the literature. There was no observable characteristic deformation of the drop prior to breakup. The time scales involved in the breakup and the resultant droplet sizes were much smaller in the phenomenon observed by us. We hypothesize that this mode of drop breakup is obtained by the combined effect of an external electric field that imposes tensile stresses on the surface of the drop, and characteristic stress-strain behavior for tensile deformation exhibited by the liquid drop in the presence of a suitable surfactant, which not only lowers the interfacial tension (and hence the cohesive strength) of the drop but also simultaneously renders the interface nonductile or brittle at high enough concentration. We have identified the relevant thermodynamic parameter, viz., the sum of interfacial tension, sigma, and the Gibbs elasticity, epsilon, which plays a decisive role in determining the mode of drop breakup. The parameter (epsilon + sigma) represents the internal restoration stress of a liquid drop opposing rapid, short-time-scale perturbations or local deformations in the drop shape under the influence of external impulses or stresses. A thermodynamic "state" diagram of (epsilon + sigma) versus interfacial area per surfactant molecule adsorbed at the drop interface shows a "maximum" at a critical transition concentration (ctc). Below this concentration of the surfactant, the drop undergoes tip streaming or pinch off. Above this concentration, the drop may undergo catastrophic disintegration if the external stress is high enough to overcome the ultimate cohesive strength of the drop's interface

Soap : the polymorphic genie of hierarchically structured soft condensed-matter products

More than 5 million tonnes of metal salts of fatty acids are manufactured and used worldwide every year, to create a range of soft condensed-matter products such as bar soaps, stick deodorants, personal care creams, toothpastes, and lubricant greases. These molecules, popularly known as soaps, are capable of forming a plethora of states and self-assembled aggregates such as micelles, liquid crystals, solid crystals, and gels, whose characteristic sizes or domain sizes can span from nanometers to centimeters. The type and mix of the phases formed, their morphologies, and their states of dispersion or the nature of their further supra-assemblies dictate the underlying micromechanical structures of products, which, in turn, are responsible for their optical, structural, and theological properties. Developing processing guidelines to manipulate characteristic micromechanical structures is therefore key to obtaining the desired look, touch, feel, and function of these products. The article discusses a few illustrative examples of these structure- property relationships demonstrated by multiscale soap assemblies. Observations of some novel tertiary structures formed by crystallizing soap fibers at the air-water interface, serendipitously discovered by us in the recent past, are also discussed, to illustrate the richness and mysteries of the well-studied and so-called mature subject of soaps

Electric field induced cloudy-clear transitions in micellar solutions of a block copolymeric amphiphile

We report observations of cloudy-clear transitions, triggered by electric fields, in micellar solutions of a poly(oxy ethylene/propylene)-poly(dimethylsiloxane) based triblock amphiphile dissolved in silicone oil (DC245). Initial studies showed complete clarification of a cloudy 2% solution at ambient temperature when subjected to a uniform electric field of similar to 5 kV cm(-1). Static Light Scattering measurements showed that the clarification was associated with a significant reduction in the size of the micellar aggregate from ca. 200 nm to 50 nm. Field strength studies at varying temperatures established the potency of the effect at 1 kV cm(-1) field equivalent to a 1 K decrease in temperature. The observed effect was qualitatively different from the electric field induced macroscopic pattern formations, or self assembled domain rotations or mesogen alignment phenomena; and quantitatively far more impactful than the minor shifts in phase boundaries reported earlier. Although the mechanistic underpinning of the observed field effect has yet to be established, the optical switchability of the solutions could be exploited for various electro-optical applications such as displays, and optical filters. The work also opens up the possibilities of using electric fields for manipulating micellar solubilization or creating tunable templates for nano-material synthesis