Data for the quenching of the fluorescence of two anthracene-derived amphiphilic fluorescence probes (ethyldimethyl-(I) and trimethyl[3-(9-anthracenyl)propyl]a"onium bromide (II)) in aqueous micellar solutions of the quencher detergents N-hexadecylpyridinium chloride (HPCl), bromide (HPBr), and nitrate (HPNO,) are analyzed in terms of a photophysical model which assumes static quenching of the micelle-incorporated probe and dynamic quenching of the residual fluorescence of the unincorporated probe by free detergent monomer and free counterions. This analysis provides values for the ground-state probe incorporation coefficient K, which are compatible with independent estimates based on the quenching of the emission of the micelle-excluded R~(bpy),~+ ion by I under the same conditions. The results of the present study clearly show that K, for incorporation of a charged amphiphilic substrate into the micellar phase of a like-charged detergent is quite sensitive to the concentration of detergent and added salt present. In addition to this general salt dependence, which can be ascribed to the effects of intermicellar ionic strength and intermicellar interactions on the micellar surface potential, the magnitude of K, also exhibits a significant specific salt (counterion) dependence. Consideration of the consequences of selectivity in counterion exchange at the micelle surface on the effective micellar surface potential provides an analytical expression which rationalizes the observed specific counterion effects on K, for this type of substrate. The implications for the quantitative analysis of ground-state reactions and equilibria in ionic micellar solution are pointed out and methods for estimating K, under diverse experimental conditions suggested.

The purpose of these studies was to evaluate chitosan films impregnated with silver sulfadiazine as potential wound dressings, based on their mechanical properties and the controlled-release phenomenon. The mechanical properties of such films were investigated under varying plasticizers (glycerol or sorbitol) concentrations, as well as in the presence of a crosslinking agent (formaldehyde). The drug release was also determined under such varying conditions, as well as using different thicknesses of film and drug concentrations. The results showed that the additives decreased the tensile strength of the chitosan films (except for sorbitol at 20% w/w), while at the same time remarkably enhancing the percentage elongation of the films. This elongation was especially pronounced in the case of glycerol. The type of plasticizer also influenced the release of silver sulfadiazine. Glycerol had a greater effect than sorbitol on the release rate, regardless of the amount used, probably due to leakage of this additive from the film, which leaves pores that enhance the water uptake of the film. As might be expected, increased concentrations of entrapped silver sulfadiazine yielded increasingly higher release rates. Decrease in thickness of the film also enhanced the release rate.

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This work presents an experimental investigation of the properties of microstrip patch antennas on bismuth niobate ceramic substrates. The substrate fabrication process and characterization are described. Several prototypes were built and measured for wireless communication systems. A good agreement was observed between measured and simulated results. The very high electrical permittivity of the ceramic substrate provided a reduction of the antenna dimensions. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1034–1036, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25098