The aim of this research is to study the bactericidal effects of copper-polypyrrole composites deposited onto 316L SS modified with silver nanoparticles. The antimicrobial properties were evaluated against twenty-four strains of Gram-positive and Gram-negative bacteria. Among the twenty-four strains studied, isolates included reference strains (E. coli ATCC 25922, E. coli 0157:H7 EDL 933, S. aureus ATCC 25923 and L. monocytogenes ATCC 7644), as well as strains isolated from food and clinical samples. The antimicrobial activity of the composites demonstrated that all PPy-modified films had antibacterial properties. Notably, Cu-PPyAgNp500 exhibited the strongest inhibitory activity against both Gram-negative and Gram-positive bacteria. Surface modification of 316L SS with these films is a promising and viable alternative for the development of novel antibacterial composites that can inhibit the growth of a significant number of bacteria.
Nature-based tourism is increasing in recent decades. In Peninsula Valdes, Patagonia Argentina, Natural World Heritage area, the tourism is one of the main economic activities of the region, based on watching marine wildlife. The southern elephant seal (Mirounga leonina) colony in Peninsula Valdes is the only continental in the southern hemisphere. The objectives of this study were to evaluate two bout groups of social actors linked to tourism (tourists and tour guides) the interest and their perception a watching elephant seals. Structured interviews to tour guides and tourists were used and developed a workshop for tour guides. Both groups agreed that watching wildlife is the main goal for the visit, and the southern right whale is the species that generates more interest, whereas the elephant seal is secondary. The experience of watching seals in their habitat was satisfactory in the different observation areas, being observation distance and number of animals, decisive factors in tourist satisfaction. Due to size, sexual dimorphism and behavior that characterizes to elephant seal it generates feelings of wonder and curiosity to the visitors and is an important resource during the guided tour. However, it is not sufficiently exploited as an opportunity to communicate conservation problems of the species or the marine habitat. The results are key tool to designing future management and planning strategies of tourism in Peninsula Valdes and adjacent areas.
RESUMEN Debido a su biocompatibilidad, biodegradabilidad y características mecánicas similares a las del hueso humano, las aleaciones de Mg constituyen una alternativa prometedora como materiales para la fabricación de implantes temporales. Sin embargo, su alta velocidad de degradación en ambiente fisiológico es un impedimento para estas aplicaciones. Con la finalidad de incrementar la resistencia a la corrosión de la aleación de Mg AZ91D en ambiente fisiológico simulado, se generaron recubrimientos dobles de cerio y epoxi modificados. Como primer paso se sintetizó químicamente polipirrol (PPy) modificado con nanopartículas de plata a partir de pirrol (Py), AgNO3 y Ce(SO4)2. Se sintetizaron dos tamaños de nanopartículas variando la concentración de AgNO3 empleada para la síntesis de los polvos. Se verificó que los compuestos tienen propiedades bactericidas contra la bacteria Gram negativa Escherichia cole (E. cori). A partir de estos resultados, se formó un recubrimiento doble sobre la aleación y éste fue modificado con los polvos sintetizados. El recubrimiento consistió en una primera película base cerio y una segunda película epoxi, a la cual se le adicionó un 1% p/p de los compuestos bactericidas. Análisis electroquímicos como polarizaciones anódicas, curvas de polarización de Tafo, variación del potencial de circuito abierto (PCA) y espectroscopia de impedancia electroquímica (EIS) verificaron que los recubrimientos modificados fueron capaces de proteger al sustrato contra la corrosión en solución fisiológica simulada. A su vez, la adición del compuesto de PPy y plata confiere propiedades antibacteriales al recubrimiento, las cuales fueron evaluadas mediante la técnica de Kirby-Bauer contra la bacteria E. coli.
The electrosynthesis of PPy films onto 316L stainless steel from nearly neutral and alkaline solutions containing molybdate and salicylate is reported. The corrosion behaviour of the coatings constituted by hollow rectangular microtubes was monitored in Ringer solution using open circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy. The polymer formed in a solution of pH 8 was the most efficient in terms of corrosion protection. The coating significantly reduced the pitting corrosion of the substrate. The results were interpreted taking into consideration the polymer electroactivity, the galvanic interaction polypyrrole/substrate and the nature of dopants. Silver species were effectively immobilized onto the hollow rectangular-sectioned microtubes of PPy. The modified coatings demonstrated that they have a good bactericidal activity against Escherichia coli and they were also able to protect the substrate against corrosion in Ringer solution.
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