Browsing by Author "Castro Narváez, Sandra Patricia (Directora)"
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Item Actividad antifúngica de Alpinia zerumbet frente a mohos y levaduras de importancia clínica(Universidad Santiago de Cali, 2020) Cruz Alemán, Lady Stephanie; Benavides Gálvez, Laura Isabel; Caicedo Bejarano, Luz Dary (Directora); Castro Narváez, Sandra Patricia (Directora)Invasive fungal diseases (EFI) diseases to susceptible hosts, cause high impact morbidity and mortality, associated with the high resistance to antimycotics of the agents etiological associated with this pathology. The antifungal activity of extracts of Alpinia zerumbet, vs. C. albicans, C. parapsilosis, C. krusei, Aspergillus fumigatus, A. terreus and Fusarium oxysporum was determined. The minimum inhibitory concentration (MIC) method and minimum inhibitory fungal concentration (CFI) based on NTC 2455 was used. As control sample, Fluconazole standard is considered and 96% Ethanol as a control. The alcoholic and hydroalcoholic extracts of the leaves and flowers affected good fungistatic and fungicidal activity when compared to the control and standard sample. It is concluded that the leaves compounds and flowers of A. zerumbet are promising for future research looking for compounds with antimicrobial activity for use in agriculture, food, and treatment of systemic mycosis.Item Análisis electroquímico de vitamina B1 con un electrodo de carbono vitreo modificado con Ni (II)(Universidad Santiago de Cali, 2025) Barona Burbano, Bryan; Castro Narváez, Sandra Patricia (Directora)Vitamin B1 (thiamine) is an essential nutrient that can be acquired through food intake; however, its deficiency can lead to diseases, which makes it necessary to have reliable and sensitive analytical methods. This research work enabled the development of an electrochemical sensor based on a glassy carbon electrode (GC) modified with nickel ions (Ni²⁺) and polyvinylpyrrolidone (PVP), which was used solely as a binding agent to attach the Ni²⁺ compound to the GC, without analyzing its electrochemical effect in this study. Measurements were carried out in phosphate buffer at different pH values. The electrode modification resulted in an increase in peak current. Studies related to the variation of the scan rate showed a decrease in oxidation potential, an increase in the heterogeneous rate constant of the oxidative process, and an increase in the diffusion coefficient (1.93×10−6 cm2⋅s −1) which indicate catalytic synergy from Ni(II). Consecutive repeatability and reproducibility analyses yielded variation coefficients below 1.78% and recovery percentages above 98% in the presence of potential interfering species such as potassium, chloride, sodium, acetate, phosphate ions, and molecules such as glucose, fructose, and sucrose. A detection limit of 0.1 µM and a quantification limit of 0.34 µM were obtained. The analysis of commercial samples of injectable medications, tablets, and syrup showed recovery percentages above 96.8%. Altogether, the results confirm that the GC/Ni²⁺-PVP electrode is an efficient, stable, and low-cost alternative for the electrochemical determination of thiamine, with applicability in the quality control of pharmaceutical products.Item Avances en materiales electrocrómicos: Perspectiva industrial en Colombia(Universidad Santiago de Cali, 2021) Hurtado Palacios, Luis Felipe; Castro Narváez, Sandra Patricia (Directora)Item Degradación del Fluconazol mediante Foto-Fenton: Aplicaciones en la agroindustria(Universidad Santiago de Cali, 2023) Martínez Sarria, Nicoll Andrea; Obeso Hurtado, Evelin Tatiana; Castro Narváez, Sandra Patricia (Directora)Fluconazole (FCZ) is one of the most widely used fungicides to combat plant pathogens which has a Fluconazole (FCZ) is one of the most widely used fungicides to combat plant pathogens which has a low degradation rate making it an emerging contaminant. The monitoring of FCZ photooxidation by UV-vis spectroscopy under different conditions such as pH, wavelength, contaminant vs. hydrogen peroxide ratio (FCZ:H2O2) and concentration of ions such as iron (II), sulfate, carbonate and phosphate establish pseudo first order kinetics by graphical method with rate constant between 0.1796 to 0.0604 min-1 and half-life between 2.41 and 11.40 min, depending on pH, FCZ:H2O2 ratio and type of ion present in the sample. The addition of carbonate (200 mg/L) to the FCZ sample evidenced a removal rate higher than 99% in 25min at pH 2.0 and a 1:4 FCZ:H2O2 ratio. Gas chromatographic studies coupled to mass detector (GC-MS) establish the obtaining of low molecular weight by-products.Item Electroanálisis simultáneo de vitaminas B1, B2, B3 y B6 en muestras farmacéuticas(Universidad Santiago de Cali, 2022) Mesías Giraldo, Sandra Milena; Castro Narváez, Sandra Patricia (Directora)An electroanalytical method was developed for the sensitive, rapid and simultaneous determination of vitamins B1 (thiamine), B2 (riboflavin), B3 (niacin) and B6 (pyridoxine). Factors such as pH, electrolyte type and scanning direction were considered in the optimization by differential pulse voltammetric determinations. The evaluation of possible interferents such as Na+, K+, CH3COO-, Cl-, PO43-, glucose, sucrose and fructose did not affect the analytical signal of vitamins when there were 10:1 ratios with respect to vitamins. Kinetic characterization, by variations of peak potential vs. sweep speed, establish heterogeneous rate constants between 153 and 1020s-1. Diffusion coefficients for vitamins in the mixture compared to individual vitamins decrease by an order of magnitude. Repeatabilities were found with %CV lower than 5% and the application for quantification in pharmaceutical samples (tablets, injectables and orals) establish recoveries higher than 93.3% with respect to the nominal value, becoming an alternative methodology for the reliable analysis of this type of samples.Item Estudio de películas de titanio-plata aplicaciones protectoras en dispositivos biomédicos(Universidad Santiago de Cali, 2021) Mina Aponza, Sebastián; Castro Narváez, Sandra Patricia (Directora); Bermeo Acosta, Franklin (Director)The search for coatings that prolong the useful lifetime of biomedical devices has been of interest, titanium being of great relevance due to its innocuousness and low reactivity. This study contributes to the investigation of Ti/Ag films in different configurations (mono and multilayer), deposited by magnetron sputtering. The sessile drop technique is implemented to study wettability, obtaining greater penetrability of the films where Ag is arranged as an external layer, confirming high efficiency in cell adhesion. The morphological properties were characterized by SEM, showing 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 crystalline phase of anatase in a proportion of 49.9% and silver forming a cubic lattice centered on the faces. Tafel polarization curves demonstrate improvements in Ag/Ti/Ag/Ti/Ag/Ti and Ti/Ag corrosion current densities versus Ag coating with 0.1749, 0.4802 and 2.044 nA*cm-2 respectively. The antimicrobial activity was evaluated against Pseudomonas aeruginosa bacteria, Bacillus subtilus and the yeasts Candida krusei, Candida albicans reveal that Ti/Ag and Ag/Ti/Ag/Ti/Ag/Ti coatings exhibit promising applications as biomedical material.Item Estudio electrocrómico de películas de óxido de molibdeno obtenidas por dip coating(Universidad Santiago de Cali, 2020) Gómez Campo, David Alejandro; Castro Narváez, Sandra Patricia (Directora)Aspects related to the influence of acetic acid and hydrogen peroxide in the synthesis of xerosols from different sources of molybdenum (MoO3, (NH4)6Mo7O24.4H2O and Na2MoO4) for the Dip Coating deposition on conductive glass substrates of dioxide. Fluorine-doped tin (FTO) applicable in the construction of electrochromic energy conversion systems. The xerosols were characterized by IR-TF, TGA, DSC and voltammetric techniques that evidence the presence of crystalline systems with thermal treatment at temperatures above 176 °C, except for Na2MoO4 sources, with crystallization enthalpies of -0.047kJ/g. Xerosols are stable between 400-750 °C and films cannot be exposed to temperatures above 800 °C because they undergo thermal decomposition. The optical band gaps (Eg) of the films range between 3,282 eV and 3,810 eV with thicknesses between 736 and 1477 nm for MoO3 and (NH4)6Mo7O24.4H2O sources and for Na2MoO4 sources they present an average band gap of 3,899 eV. The electrochemical activation of the films consisting of potential step (-2.0 V to 2.0 V vs AgCl), in the presence of 1.0 M LiClO4 solution in PC established a color change in the light brown film with an increase in absorbance at 490 nm. Annealing films show yields of changes in transmittance between the light and dark state between 1.38 and 49.3%, coloring efficiencies () that range between 58.25 to 0.037 cm2 C-1 that are dependent on temperature and the type of xerosol used in the deposition. The use of acetic acid and hydrogen peroxide in the synthesis of xerosols imparts greater electrochromic efficiency to the films compared to those that not are treated.Item Estudios mecánicos y microbiológicos de películas de almidón de yuca funcionalizadas con óxido de zinc y piperina(Universidad Santiago de Cali, 2022) Polindara Ospina, Gustavo Adolfo; Franco Araujo, Robert Felipe; Castro Narváez, Sandra Patricia (Directora); Caicedo Cano, Carolina (Directora)In recent decades, there has been a growing interest in replacing petroleum-based plastic packaging materials with biodegradable materials. Thermoplastic starch has emerged as a low cost and low environmental impact alternative. This study reports mechanical and microbiological properties of biodegradable films of cassava starch and glycerol as plasticizer, manufactured by casting method and functionalized with polyvinyl alcohol (PVOH), zinc oxide and piperine extract. All the films show a thickness variation of 119.9 ±1.1µm and high transparency higher than 90%, which decreases with the amount of ZnO reaching 75%. The Fourier transform infrared (FTIR) and Raman spectra show bands characteristic of starch, PVOH and ZnO, as well as displacement of the bands associated with hydrogen bridge intermolecular forces between the starch polymer, PVOH copolymer and ZnO. Calorimetric analyses (TGA and DSC) show a reduction in mass loss of 128% and tensile strength establishes that ZnO functionalized films are more stable and with better mechanical performance (10.83 MPa). The starch functionalized films show lower adherences to Escherichia Coli, Salmonella Aureus, the fungus Aspergillus Niger and the yeast Candida Albicans compared to the non-functionalized films. The obtained results together with the cost analysis allow the development of films for the manufacture of flexible packaging that do not require subsequent treatments for printing and lamination because they present surface energies higher than 40 mN/m.Item Incidencia pos-cosecha en frutos de aguacate var. Hass frente a la aspersión de un bioestimulante foliar de silicio(Universidad Santiago de Cali, 2023) Forero Rodríguez, Oswaldo; Castro Narváez, Sandra Patricia (Directora); Patiño, Oscar (Director)The commercial and agroindustrial progress of avocado var. Hass in the country leads to the search for agronomic strategies to improve fruit quality, both in terms of shelf life and resistance to transport. This study establishes for the first time the impact of a silicon foliar fertilizer on Hass avocado crops. Incidence was evaluated by pre-harvest spraying and post-harvest fruit quality criteria. The addition of calcium silicate foliar fertilizer (Si: Ca ratio of 0.66) reduced the presence of free water in leaves, stems and fruit, which led to a decrease in the loss of weight and firmness of the fruit in postharvest storage. Likewise, a delay in the ripening process of the fruit was observed between one and two weeks with respect to the control. Physicochemical parameters such as increase in °brix, % titratable oleic acid and decrease in respiration rate with respect to CO2 and ethylene generation were found with the foliar treatment. The respiratory quotient (CR) in treated fruits are aerobic with carbohydrate consumption and in high dosages via fermentative anaerobic due to the creation of a silicon cuticle that decreases the respiratory processes. Photographic studies establish a 50% decrease of fruits in poor condition in week 5 of storage. The project benefits avocado farmers and also favors the commercialization of the fruit nationally and internationally by making the fruit less vulnerable to deterioration during transport. Likewise, the research opens new studies towards the determination of water stress in this avocado variety with and without the application of silicon-based stimulants.Item Mejoramiento de la calidad de agua residual de una industria gráfica por método fisicoquímico y tratamiento Fotofenton(Universidad Santiago de Cali, 2020) Castro Ordoñez, Oscar Eduardo; Morales Lame, Ronal Leonel; Castro Narváez, Sandra Patricia (Directora)Wastewater samples from flexographic printing machines of the graphic industry characterized by having high coloration, low pH, high oxygen demand and low biodegradability to primary physicochemical treatment followed by photofenton process with the objective of reducing chemical oxygen demand (COD). Initially, the pouring generator washing process was standardized, the primary treatment consisted of coagulation with aluminum polyhydroxychloride or ferric chloride, followed by filtration with activated carbon. The Fenton process was optimized by varying the pH, and the particles of iron and peroxide. The standardization of the washing process generated a 50% COD reduction, in the primary treatment, aluminum polyhydroxychloride was the best performance. After one hour of treatment with the photofenton process with UV lamp at pH: 4.0; 40.0 mgL-1 of Fe2+ and 200 mgL-1 of hydrogen peroxide, a 97% removal was processed. Thus, by coupling the physicochemical treatment with the photofenton process, the environmental impact of the wastewater of the graphic industry is reduced.Item Obtención y caracterización de derivados de carbono con posibles propiedades tecnológicas a partir de cáscara de cacao(Universidad Santiago de Cali, 2023) Ocampo Calvo, Juan Manuel; Castro Narváez, Sandra Patricia (Directora)Carbonaceous materials from agro-industrial wastes were synthesized to provide a phytosanitary management to the problems presented in cocoa plantations and to give an added value to the by-products coming from the shell of this fruit. The products were obtained by impregnation with H3PO4 of the raw material and later heat treatment at 600ºC for 2 hours and 4 hours to obtain activated carbons that were oxidized by the modified Hummers method and a reduction with ascorbic acid, The products obtained were characterized by calorimetric (TGA-DSC), spectroscopic (UV-Vis, IR-TF, Raman), morphological (SEM), Zeta potential, particle size) and electrochemical (VC, EIE) techniques, finding that the oxidized species are more suitable as raw material in the manufacture of supercapacitors. This study contributes to the cocoa agroindustry by giving an added value to cocoa shells; it also opens a door to the study of supercapacitors obtained with a sustainable concept.Item Propiedades electrocrómicas de películas de WO3 obtenidas por deposición electroquímica(Universidad Santiago de Cali, 2022) Valencia Marín, Jose Manuel; Castro Narváez, Sandra Patricia (Directora)Contributions are made to scientific-technological research oriented towards sustainability, specifically in the construction of smart windows. The influence of different acids (HCl, H2SO4, HNO3, HClO4 and CH3COOH) on the morphology and composition in the synthesis of WO3 was studied. Infrared (IR-TF), scanning electron microscopy (SEM) and X-ray diffraction (XRD) results establish that the acids form flat-faced oxides with edges, resembling their crystalline habit to prismatic and in the case of H2SO4 and HNO3, agglomerates are observed that are configured in crystalline niches with nanoflower-like pores in which multistage decomposition is present. The crystalline composition of the xerosols was hydrated and unhydrated tungstite. In spectroelectrochemical studies, electrochemical deposition of WO3 films on FTO substrates and sintering between 300 and 500°C exhibit high transmittance (85 - 100%), thicknesses between 600 and 712nm and dark yellow coloration in the colored state, which are independent of the acidulation source of WO3 xerosol synthesis. The optical band gaps ranged from 3.19eV to 2.20eV and electrochemical band gaps from 2.47eV to 2.69eV. The coloring efficiency of the deposited films shows a slight dependence on the acidity of the acid source used in the xerosol synthesis and on the sintering temperature. The oxides synthesized with CH3COOH and HClO4 presented better contrast and optical density.Item Validación de limpieza del área de volúmenes bajos 2 en una industria farmacéutica del Valle del Caucа(Universidad Santiago de Cali, 2024) Orejuela Salcedo, Stefania; Castro Narváez, Sandra Patricia (Directora)Ensuring the cleanliness of equipment in the veterinary pharmaceutical industry is a priority, since improper handling can generate incompatibilities between drugs. This study contributes to the cleaning validation activities in the low volume session of a pharmaceutical company. To this end, a risk analysis was initially carried out by the effect and failure methods (AMEF) using the 6M (Manpower, Measurement, Machinery, Method, Environment and Material). Subsequently, the compound categorized as the “worst case” was weighted to the active Meloxicam, giving an acceptable residue limit (ARL) of 1.5 ppm. High performance liquid chromatography (HPLC) allowed separation and quantification of meloxicam in a retention time of 5.3 min. Linearity was evaluated at 5 points from 40 to 140% obtaining a correlation coefficient of 0.9991, with a limit of detection (LOD) of 0.0602 ppm and limit of quantification (LOQ) of 0.182 ppm. Accuracy exhibited a %RSDp of 1.4%, accuracy with three different concentrations at 60%, 100% and 140%, allowed recovery percentages between 99.5 to 103.4%. Meloxicam exhibited greater stability at 4°C over a period of 84h. The implementation of the cleaning protocol in the low volume session established that no rejections or alerts were observed, consolidating the cleaning practices as an assertive method in the prevention of cross-contamination with other products.