Facultad de Ciencias e Ingeniería

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    Estudio de la bioactividad de compuestos polifenólicos extraídos de cacao y su efecto en enfermedades asociadas a la obesidad
    (Pontificia Universidad Católica del Perú, 2025-01-15) Robles Santivañez, Angela Ximena; Kim de Aguilar, Suyeon
    En el Perú, el 24.6% de la población mayor a 15 años tiene obesidad, la cual es el principal factor de desarrollo de hipertensión arterial y diabetes. La diabetes es una de las enfermedades crónicas no transmisibles que más afectan la salud humana y puede causar la muerte debido a diversas complicaciones que se presentan a lo largo del tiempo. Esto exige el estudio de alternativas de alimentos que posean propiedades bioactivas para detener o prevenir el proceso de la enfermedad. La biodiversidad del país ofrece alimentos ricos en compuestos fenólicos, a los cuales se les atribuye propiedades antioxidantes y antiinflamatorias. En el presente trabajo se evalúa la bioactividad de los extractos fenólicos obtenidos de granos de cacao. Como parte de este objetivo, se optimiza los parámetros para obtener extractos con la mayor cantidad fenólica posible. Aquellos extractos se caracterizan en base a su contenido fenólico total -mediante el método de Folin-Ciocalteu- y a su capacidad antioxidante equivalente a trolox (TEAC) -por medio del método con ABTS. Al evaluar los extractos en ambos, se determina que el uso de solvente influye de manera significativa sobre la extracción. El uso de acetona como solvente permite obtener extractos con un contenido fenólico de 532 µg/ml en equivalentes de ácido gálico y alcanza una capacidad antioxidante de 31%, el cual aumenta con respecto al tiempo y a la concentración. Asimismo, se demuestra su efecto en la diabetes mediante la inhibición de las enzimas α- glucosidasa y lipasa, lo cual convierte al extracto en un compuesto bioactivo con alto potencial para prevenir la enfermedad. El cacao es un recurso natural abundante en el país, por lo que, el estudio de este alimento, generaría un mayor impacto a futuro.
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    Optimization of the alkaline treatment for Agave americana fiber and its influence on the mechanical properties of fly ash-based geopolymer
    (Pontificia Universidad Católica del Perú, 2021-08-25) Rojas Clemente, Shirley Melanie; Kim de Aguilar, Suyeon; Aguilar Vélez, Rafael
    Geopolymers are good alternatives for replacing ordinary Portland cement (OPC) due to their comparable properties and feasibility to be obtained from industrial by-products. As OPC, geopolymers have superior compressive strength but a brittle behavior that the addition of fibers can improve. When the first macrocrack appears, fibers develop bridging mechanisms to allow the proper distribution of loads, so the composite can enable multiple cracks and enhance its ductility. At present, a wide range of materials can be used to reinforce cementitious matrices, from synthetics such as steel, glass, carbon, and polypropylene to natural fibers such as cotton, sweet sorghum, oil palm, coir, jute, sisal, flax, bamboo, etc. Natural fibers are among the most accepted resources to reinforce composites because they are biodegradable, renewable and generally, have a less environmental impact than their synthetic counterparts. They have low density and specific mechanical properties comparable to fibers made of glass, making them materials with a good performance-price ratio. However, their high variability of properties and hydrophilic behavior can create issues when reinforcing a matrix. Chemical treatments are used to clean chemical compounds that do not contribute to the fiber strength and favor moisture absorption. After treatment, the fiber surface increases its roughness which enhances the interlocking within the composite. This thesis investigates the mechanical properties of Agave americana fibers obtained by beating and boiling the leaves. The fibers were subjected at 1%, 5%, and 20% NaOH concentrations over 0.5 hr, 1 hr, and 3 hr and tested to determine the tensile strength. The surfaces were also analyzed by scanning electron microscopy (SEM). After treatment, most of the fibers enhanced the tensile strength and strain and 1% NaOH concentration over 1 hr was chosen as the optimum condition. Then, fibers were treated at the optimum condition and added to the geopolymer mixture at different doses: 0.5%, 0.75%, and 1% by weight of fly ash. The geopolymers were tested at compressive, flexural, and splitting tensile loads at 7 days of age. The compressive strength increased by 12% at 0.75 (wt.%) and the modulus of elasticity in compression, 13% at 1% (wt.%). Also, the tensile strength increased by 36% at 1 (wt.%). However, the flexural strength decreased probably due to the fiber length. Still, further studies are needed to understand the influence of the fiber length on the mechanical properties of geopolymers. Finally, the SEM analysis was conducted to identify the fiber failure modes.