Alginate hydrogels incorporating neomycin or propolis as potential dressings for diabetic ulcers: Structure,swelling, and antimicrobial barrier properties

Alginate hydrogels have many attractive characteristics for potential use as wound dressing materials. However, they are not considered to possess any intrinsic activity against microbial infection, often present in neuropathic wounds. To overcome this, the effect of incorporating neomycin or propolis in alginate hydrogels was investigated, both by direct blending alone and also by further addition of loaded alginate microparticles prepared by the extrusion dripping method. The morphological, microstructural, thermal, mechanical, and swelling properties of each film were evaluated, as well as particle size distribution and antimicrobial penetration analysis. Microparticle size was considered suitable for drug delivery applications and incorporation in hydrogel films. The presence of neomycin and propolis, in both blended and microparticle form, interfered with film properties leading to hydrogels with different characteristics. All samples showed swelling degrees up to 100% and mechanical and thermal properties suitable for application as wound dressings. In addition, all samples acted as barriers to microbial penetration.     

A Fractional Linear System View of the Fractional Brownian Motion

A definition of the fractional Brownian motion based on the fractional differintegrator characteristics is proposed and studied. It is shown that the model enjoys the usually required properties. A discrete-time version based in the backward difference and in the bilinear transformation is considered. Some results are presented.     

Generalized multiple-prism dispersion theory for pulse compression in ultrafast dye lasers

A generalized multiple-prism dispersion theory, applicable to pulse compression schemes in femtosecond dye lasers, is described. The equations can be utilized to determine the dispersive characteristics of any multiple-prism arrangement. Also, the difference in dispersive values resulting in the use of various prism materials, including ZnSe, is compared.     

A double-prism beam expander for pulsed dye lasers

The design of a pulsed dye laser cavity incorporating a double-prism beam expander is described and operating characteristics compared with those of single-prism systems. Narrow spectral linewidths (δλ = 0.008 Å) are achieved at relatively high efficiency (> 10%) for coumarin 500 dye solutions. Background superfluorescence in the output is low and the cavity is free from external coupling effects.     

Returns to the time axis in directed configurations

Directed configurations in dimensions 2 to 4 are investigated regarding the average number of returns to the anisotropy, or time, axis. Series expansions for this quantity, show that it vanishes asymptotically with a dimension dependent exponent equal to the critical exponent for directed animals in the corresponding dimensionality.     

On the approach to the final aperiodic regime in maps of the interval

We present a global approach to the final aperiodic regime in maps of the interval displaying a simple pattern with similarities to the Feigenbaum scheme.