Browsing by Author "Caguana Reyes, Stefania Tania"

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    Metal nanoparticles obtained by green hydrothermal and solvothermal synthesis: characterization, biopolymer incorporation, and antifungal evaluation against Pseudocercospora fijiensis
    (Universidad de Cuenca, 2025-03-12) Caguana Reyes, Stefania Tania; Cruzat Contreras, Christian Américo
    Nanoparticles (NPs) have generated significant interest in various fields due to the unique properties that materials exhibit at the nanoscale. This study presents a comparative analysis of copper nanoparticles (Cu-NPs) and cobalt nanoparticles (Co-NPs) synthesized via conventional solvothermal and green hydrothermal synthesis using ethylene glycol and Medicago sativa extract, respectively. The conventional solvothermal synthesis showed higher efficiency for both Cu-NPs and Co-NPs with yields of 32.5% and 26.7%, respectively. Characterization through UV–visible spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) revealed that while solvothermal synthesis produced larger particles (76.5 nm for Cu-NPs, 86.8 nm for Co-NPs), the green hydrothermal method yielded smaller particles (53.8 nm for Cu-NPs, 67.7 nm for Co-NPs) with better control over particle size distribution and spherical morphology, showing minimal agglomeration. UV–vis confirmed metal oxide formation, while FTIR showed complex patterns in NPs (green hydrothermal), indicating plant extract compounds. Antifungal evaluation against Pseudocercospora fijiensis showed complete inhibition at 2000 ppm for both NP types, with no mycelial growth after 30 days. When integrated into chitosan, solvothermal NPs produced rougher surfaces, and scanning electron microscope (SEM) confirmed the presence of copper and cobalt in the nanocomposites. This study provides insights into the synthesis of nanoparticles using an environmentally friendly process and their microbiological applications for future use in organic agriculture.
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    Utilización de herramientas geoestadísticas para la generación de información espacial meteorológica en la provincia del Azuay
    (2017) Caguana Reyes, Stefania Tania; Mejía Coronel, Julio Danilo
    Meteorological information has become, at present, in a factor of great importance for the development of several human activities, since it allows to know the climatic characteristics of a place, facilitating to carry out this activities with success. One of the tools that allow to obtain this type of data of places in which there are no meteorological stations, are the geostadistic methods. The present research work had the objective of generate precipitation and temperature information from the Azuay Province (northeastern zone), through a geostatistical analysis based on hourly data collected in 16 meteorological stations belonging to the Corporación Eléctrica del Ecuador (CELEC) and to the Universidad Politécnica Salesiana (UPS). The methods of analysis used were the Kriging and Cokrigin, using as modeling tool the ArcGis software. The results indicate an average-hour temperature in a range of 5.86 to 20.23 °C and an average-hour rainfall in a range of 0.05 a 0.32mm for the different zones of the province. In addition the process showed that the multiple linear regression method and the arithmetic mean method are adequate to complete the missing meteorological information and that the Gaussian Ordinary Kriging method is the model that best fits the study variables and therefore is the best interpolation method for time-scale variables. The results obtained will be shared and implemented in a geoportal, which allows the access to this information purified to different users.