no. 14 (enero abril 2016)
Permanent URI for this collectionhttps://dspace-test.ucuenca.edu.ec/handle/123456789/25052
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Item Avances en el proyecto “Determinación de la forma exacta de la tierra a través de MEMS en un Nano-Satélite”(Universidad de Cuenca, 2016-04) Vázquez, J. Félix; Fernández, Tiburcio; Viniegra, F.The following document illustrates the progress that has been made in the “Design and construction of a Nano-Satellite” project. It is currently under development at ESIME U.P. Ticoman, which is part of the Instituto Polit´ecnico Nacional. The Projects main objective is to give our students an introduction into Aerospace issues. The Nano-Satellite is a small cubic shaped devise measuring ten centimeters per side, with a one kilogram total weight. Its payload is a MEMS (Micro Electro-mechanical Systems) which will act as an electronic pendulum; this, combined with the gravitational potential harmonics, will allow us to determine the Earths true shape. The mathematical foundation, satellite components, preliminary structure design, manufacturing process, results of the structural destructive tests and static Analysis through the finite element method, are shown in this presentation.Item Modelado cinético y matemático de la reacción de gasificación catalítica de la glucosa en agua en condiciones supercríticas para la producción de hidrógeno(Universidad de Cuenca, 2016-04) Zalamea, Silvana; Mejía, William; Serrano, JoséHydrogen produced from banana biomass waste is considered as a highly efficient biofuel. One of the cleanest methods for its obtention is the catalytic supercritical water gasification, wherein the constituent polysaccharides of biomass (cellulose, hemicellulose and lignin) convert into high value gaseous products. It is important the design of a chemical reactor for this process due to the necessity of achieving the hydrogen production in a reliable way. Among the elements that determine the reactor design, in this article were studied the intrinsic kinetic and material balance. First, a kinetic study of the reaction was performed using the glucose as model compound owing to it is the most important structural component of the cellulose. It was revealed several intermediate reactions that influenced on the yield for hydrogen. Later, it was performed a differential species balance for the glucose. It was solved in Fortran 95 applying the Thomas numerical algorithm. The results showed that at lower mass fractions of glucose, the higher levels of conversion.Item Is there a need for “healthy” chocolate? Systematic literature review(Universidad de Cuenca, 2016-04) Vintimilla Alvarez, María CeciliaBackground: Chocolate has special properties that help to protect the human body against cardiovascular diseases; it increases HDL cholesterol and decrease blood pressure. Chocolate consumption also helps to reduce stress, elevates mood and reduces tiredness. The purpose of this review is to identify, select, organize and summarize studies that investigate chocolate in relation to health, sensory characteristics and people’s attitudes. This report is part of the master thesis: Is there a need for “healthy” chocolate? Systematic literature review and consumer research in Belgium and in Denmark, submitted by the author in June 2015 at Aalborg University in Copenhagen. Methods: This study presents three areas related to chocolate: Chocolate and its relation to health, Chocolate sensory characteristics and acceptance, and attitudes towards Chocolate. A systematic literature review has been done to identify, select, organize and summarize studies that investigate chocolate in relation to these three areas. Four databases were chosen: PubMed, Science Direct, Scopus and Web of Science because of their extension and because they overlay cross disciplinary researches. Results: A total of 2062 hits were obtained in the four databases. In total sixty articles met the criteria and were identified as relevant. The articles were classified according to the three areas included in the study. In relation to health, it has been stated in many studies that polyphenols in chocolate can improve health, especially cardiovascular diseases related. Regarding sensory characteristics and acceptance of chocolate, it has been said that chocolate shape has an influence on chocolate perception. Polyphenols cause astringency and bitterness to chocolate making it not too appetizing for consumers; however for health reasons, polyphenols should be kept. Concerning the attitudes towards chocolate, there are many factors that lead to chocolate craving. Chocolate is the most craved food item in North America. It influences people’s mood and create a satiety feeling. Conclusion: Based on this review it can be concluded that a “healthy” chocolate could be part of a healthy diet. People like to indulge in chocolate, women more than men. The literature supports the health properties that chocolate consumption has, for instance, it is necessary to work on chocolate product development.Item UV-Vis, FTIR and antioxidant study of Persea Americana (Avocado) leaf and fruit: A comparison(Universidad de Cuenca, 2016-04) Kumar, Brajesh; Cumbal, LuisAvocado (Persea americana Miller), a well-known nutritional tree crop grown in many parts of the world. The present study compares the UV-Vis and Fourier transform infrared spectroscopy (FTIR) spectrum of Avocado leaf and fruit (peel, pulp, and oil) cultivated in Ecuador; and further its antioxidant activity is evaluated against 1,1-diphenyl-2-picrylhydrazyl (DPPH•). The UV-Vis and FTIR study revealed predominant amount of flavonoids. Among the Avocado leaf and fruit studied, the DPPH• free radical scavenging assay for Avocado leaf had the highest antioxidant activity ranging from 84.46 % to 80.12% with values from 32.60-32.73 μg gallic acid equivalents per mL. It showed that the order of antioxidant activity in Avocado is leaf > peel > oil > pulp. The antioxidant activity had a positive correlation with total flavonoid content and these plant extracts (specially Avocado leaf) are useful for future antioxidant products.Item Efecto antiinflamatorio de extractos metanólicos de plantas de Azuay y Loja (Ecuador) a través del modelo de peces cebra(Universidad de Cuenca, 2016-04) Peñaherrera, Eugenia; Jerves Andrade, María de Lourdes; Cuzco, Nancy; Wilches, Isabel; León Tamariz, Fabián; Tobar Solano, Vladimiro AlexisThe biological model of zebrafish has been widely used in primary screening of plant extracts for antiinflammatory effect, due to its genetic, physiological and pharmacological response similarities to mammals. The present study evaluated the antiinflammatory activity of 36 methanol extracts prepared from medicinal plants used by communities in the provinces of Azuay and Loja (Ecuador). The plant material was collected with the support of a Saraguro herbalist. The extracts were prepared by percolation and the toxicity was evaluated in zebrafish model at concentrations ranging from 400 to 3,125 μg/ml; determining the maximum tolerable concentration. The antiinflammatory activity was analyzed by using the leukocyte migration test induced by lipopolysaccharide of Sallmonella typhi. Extracts of: Cestrum aff. peruvianum, Galinsoga parviflora, Galium sp., Oenothera tetraptera, Peperomia aff. galioides , Passiflora ampullaceae and Ambrosia arborescens, equivalent to 18,92% of the analyzed ones, have antiinflammatory potential comparable with the positive controls indomethacin and dexamethasone; being the methanol extract of Cestrum aff. Peruvianum (50 μg/ml), the most relevant. The phytochemical analysis of the extracts by Thin Layer Chromatography showed the presence of saponins and terpenoids as the principal components in most of the extracts.