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Ítem Desarrollo de sensores electroquímicos para la determinación de drogas sintéticas en fluidos biológicos y muestras de incautación(2023-07-09) González Hernández, Jerson; Alvarado Gámez, Ana LorenaLa cantidad de nuevas sustancias psicoactivas, popularmente conocidas con términos como: drogas emergentes, drogas de diseño, drogas sintéticas o drogas recreativas, aumenta en el mercado global de las drogas cada año. El uso de nuevas tecnologías para la producción y la comercialización de las sustancias, aunado a una demanda exigente de nuevos efectos psicotrópicos más potentes, son algunos de los factores que contribuyen al incremento de una oferta más variada, así como a la cantidad de consumidores de algún tipo de psicoestimulante a nivel mundial. A raíz del potencial demostrado de los sensores para el análisis de drogas, se desarrollaron cinco sensores electroquímicos de la siguiente manera: tres sensores basados en transductores de carbono, platino y diamante dopado con boro para la determinación de 25B-NBOMe, DMT, BZP y mCPP en fluido oral con límites de detección entre 0.15 µg/mL y 1.8 µg/mL, un sensor espectroelectroquímico de Raman para el análisis selectivo de las catinonas 4-MMC y 4-MEC en orina y en muestras de incautación (límites de detección de 6.6 µg/mL y 2.4 µg/mL para cada molécula respectivamente) y un biosensor enzimático para la cuantificación de fentanilo en muestras de orina con un límite de detección de 0.086 µg/mL y con porcentajes de recuperación entre el 92% y 100%. El desarrollo de herramientas analíticas fiables y robustas, con la capacidad de respuesta in situ para una evaluación preliminar, contribuyen significativamente con la generación de información científica para la atención adecuada de diversas situaciones. Los sensores electroquímicos han ganado terreno en áreas como la toxicología y las ciencias forenses. Esencialmente, porque son dispositivos portátiles de fácil manipulación, altamente versátiles, con mínimos requerimientos en el tratamiento de la matriz y que necesitan cantidades muy pequeñas de muestra. Asimismo, las metodologías electroquímicas –en las que se basa la medición de los sensores– presentan excelentes parámetros de desempeño como bajos límites de detección, alta sensibilidad y muy buena precisión.Ítem Evaluación de los efectos de la contaminación atmosférica y el ángulo de exposición sobre la corrosión del acero de bajo carbono y acero galvanizado en la región del Valle Central Occidental (VCO) de Costa Rica(2023-05) Rodríguez Yáñez, Javier E.; Sanabria-Chinchilla, JeanCosta Rica is a country that imports its metallic materials, this makes the evaluation of its corrosion losses of special interest, since they represent an average of 3% of the GDP. In particular, atmospheric corrosion is more than 50% of these losses, so their evaluation in basic metallic materials is a necessity. In this sense, the Western Central Valley (WCV) is the area with the largest population and economic activity in Costa Rica, so the development of this analysis in this area is a priority. This thesis proposes the estimation of the values of atmospheric corrosion for WCV for low carbon steel (like A36) and galvanized iron, as the main consumer products at the country level for the construction of metallic structures. The evaluations were based on the ISO 9223 and associated standards, both for the corrosion process and for the climate and main atmospheric pollutants evaluation during a 24-month period. The pollution levels are low, so the corrosion is controlled mainly by atmospheric parameters, especially the time of wetting (TOW). Furthermore, the corrosion corresponds to a C2 level for both materials. The study proposes a series of meteorological maps associated with the area, as well as annual corrosion maps derived from these, and a proposal of the variability established for the different angles of inclination in steel. The information is complemented for steel with the characterization of the oxides formed, through surface analysis by electron microscopy and X-ray diffraction. As well as their basic analysis by electrochemical techniques.Ítem The geomicrobiology of iron, cobalt, nickel and manganese in lateritic tropical soils from the Santa Elena Peninsula, Costa Rica(2019) Solano Arguedas, Agustín; Lloyd, Jonathan R.There is an increasing interest in the biogeochemistry of metals, like cobalt, fuelled by the growing need for batteries and other high technology products. Bioprocessing of Co has been proposed to improve its recovery from Ni-rich laterites, but the natural biogeochemistry of Co and other metals associated such as Fe, Ni and Mn in laterites is still relatively unexplored. In Costa Rica, the Santa Elena Peninsula is closely associated with the Santa Elena Ophiolite, and the tropical climate alongside the lack of anthropogenic alteration for nearly 50 years, make this a unique area to study natural biogeochemical processes in a laterite/serpentine context. This thesis therefore aimed to understand the biogeochemical cycling of Fe, Co, Ni and Mn in the lateritic soils of the Santa Elena Peninsula. The geochemical composition, mineralogy and microbial structure (prokaryotic and fungal) of these soils were described for the first time, considering a landscape approach. Three types of lateritic soils were identified based on the geochemistry, geography and microbial composition: mountain soils, inner ophiolite lowland soils and north lowland soils. Each type of soil was studied using fluctuating redox microcosm experiments to emulate a complete anaerobic-aerobic cycle. With glucose biostimulation, bioweathering and biomineralisation of Fe/Mg minerals were more intense in the mountain soils and mediated by microbial Fe redox cycling, while methanogenesis was enhanced in the lowland soils, highlighting the potential importance of these lateritic systems for carbon fluxes. For a better understanding of the natural conditions underpinning those biogeochemical cycles, the fluctuating redox microcosm experiments were extended by using samples from both dry and wet seasons and using cellulose as an electron donor analogous to the natural plant matter found in the soils. Under anoxic conditions mobilisation of Co, Ni and Mn was enhanced by microbial cellulose degradation and linked to microbial Fe(III) reduction and bioweathering of Fe-oxides. However, when oxic conditions were imposed, Co, Ni and Mn solubilisation increased, likely associated with the bioweathering of Mg minerals including hydrous silicates or clays but still linked to cellulose degradation. Organisms affiliated with the Firmicutes played a key role in these processes, likely degrading cellulose into smaller molecules bioavailable for other microbial processes such as Fe redox cycling (or metal chelation). Other microorganisms found that could be directly or indirectly associated with the cycling of Co, Ni and Mn included Fe(III) and Mn(IV) reducing bacteria, methanogens and fungi. Seasonal precipitation was key to induce redox processes in the serpentine soils by facilitating the development of anoxic conditions, and the impact depended on the soil geographical/geochemical origin. Despite the unique environment of the Santa Elena Peninsula, some of the results of this thesis supported previous observations in laterites and serpentine areas worldwide, evidencing the potential of the Santa Elena Peninsula as a model location to understand natural biogeochemical cycles in tropical serpentine ecosystems; but with outcomes that can also be extrapolated to other sites, landscapes and ecological contexts.