Browsing by Author "Castro Narváez, Sandra Patricia"
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Item Conductimetry: a rapid alternative technique for chlorides determination in cheese(Universitas Scientiarum, 2019) Aguirre Londoño, Jessica; Aristizabal Ferreira, Víctor Alexander; Castro Narváez, Sandra Patricia; Ramírez Navas, Juan SebastiánThe correlation of two instrumental techniques for chlorides determination in Colombian cheese, Queso Molido Nariñense (a type of white cheese), was analyzed. Potentiometry of chloride precipitation is the standard technique to determined salt in cheese. Conductimetry is an alternative technique. Samples of Queso Molido Nariñense were made. In the processed cheeses the salt concentration (NaCl: 0.5 %, 0.8 %, 1.0 %, 2.0 %, 3.0% and 6.0 %) was varied. Chlorides were determined by titration with silver nitrate in the potentiometric technique. In the conductimetric technique, each sample was analyzed by direct measuring its conductivity at room temperature. It was found that there is an adequate correlation between potentiometry and conductimetry. A maximum concentration of 2% NaCl in cheese is equivalent to 2.9 S/cm for conductivity readings. Additionally, it was verified that the conductimetry constitutes an analytically reliable technique for the determination of chlorides in cheese, it is friendlier to the environment, cheaper and faster.Item Correlation between sensory and instrumental measurements of saltiness in Queso Molido Narinense(2021) Ramírez Navas, Juan Sebastián; Aristizabal Ferreira, Víctor Alexander; Aguirre Londoño, Jessica; Castro Narváez, Sandra PatriciaA sensory study was conducted at the Universidad Santiago de Cali with Queso Molido Nariñense. To determine the preferred levels of concentration acceptable by consumers, samples were made with different concentrations of NaCl (C1 = 0.62%, C2 = 0.87%, C3 = 1.05%, C4 = 1.74%, C5 = 2.71%, and C6 = 5.34%). The results show that sample C4 had the highest degree of acceptance, followed by C2, C3, and C5, while C1 and C6 had the lowest acceptance. Consumers were able to distinguish salt differences above 0.27%. It was possible to predict consumer reaction regarding their levels of acceptability and perception using the Sensory-Instrumental correlation. This result showed that either an extremely low or a very high level of concentration of salt in cheese could result in a low acceptance by consumersItem Study of titanium–silver monolayer and multilayer films for protective applications in biomedical devices(2021) Mina Aponzá, Sebastián; Castro Narváez, Sandra Patricia; Caicedo Bejarano, Luz Dary; Bermeo Acosta, FranklinThe search for coatings that extend the useful life of biomedical devices has been of great interest, and titanium has been of great relevance due to its innocuousness and low reactivity. This study contributes to the investigation of Ti/Ag films in different configurations (monolayer and multilayer) deposited by magnetron sputtering. The sessile droplet technique was applied to study wettability; greater film penetrability was obtained when Ag is the external layer, confer-ring high efficiency in cell adhesion. The morphological properties were characterized by SEM, which showed porous nuclei on the surface in the Ag coating and crystals embedded in the Ti film. The structural properties were studied by XRD, revealing the presence of TiO2 in the anatase crystalline phase in a proportion of 49.9% and the formation of a silver cubic network centered on the faces. Tafel polarization curves demonstrated improvements in the corrosion current densi-ties of Ag/Ti/Ag/Ti/Ag/Ti/Ag/Ti and Ti/Ag compared to the Ag coating, with values of 0.1749, 0.4802, and 2.044 nA.m−2, respectively. Antimicrobial activity was evaluated against the bacteria Pseudomonas aeruginosa and Bacillus subtilis and the yeasts Candida krusei and Candida albicans, revealing that the Ti/Ag and Ag/Ti/Ag/Ti/Ag/Ti/Ag/Ti coatings exhibit promise in biomedical material applications.Item Trends in Electrochromic Materials: Industrial Perspective in Colombia(Universidad Nacional de Colombia, 2024) Hurtado Palacios, Luis Felipe; Castro Narváez, Sandra Patricia; Jaramillo Aguirre, AlonsoDissertations across various sectors (industrial, governmental, and research) advocate for the manufacture of products with innovative scientific and technological developments as a driving force to generate added value and, in a dual approach, respond to the expectations of domestic consumers and encourage exports in the country. This analytical and descriptive bibliometric review on electrochromism, a property of some materials that allows them to reversibly change their optical transmittance via the repeated and consecutive intercalation and extraction of electric charges under a small alternating polarity electric potential, contributes by describing the fundamentals, recent research advances, and the feasibility of national industrial application, given the existence of mineral resources, chemical inputs, companies, and qualified human talent at different levels of sectors related to chromic devices and energy storage.