Browsing by Author "Caicedo, Carolina"
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Item Bio- energía trabajo muscular y respiración en la córnea(Informador Técnico, 2018) del Castillo, Luis F.; Ramírez-Calderón, Juanibeth G.; Caicedo, Carolina; Ávila-Torres, Yenny; Caicedo-Cano, Diego F.; Compañ, VicenteResumen En este artículo de revisión se presentan dos casos del área de bioenergía en relación con la producción de energía vía descomposición del trifosfato de adenosina (ATP). El primero, es el trabajo que realiza el cuerpo humano debido a la contracción del músculo esquelético y el segundo el proceso de difusión de oxígeno en la córnea. Se exponen los antecedentes químico-físicos de la producción y utilización de la molécula energética por excelencia del ATP. Se analizan desde el punto de vista termodinámico, la generación de moléculas bioenergéticas tanto en la respiración aeróbica como en glicólisis anaeróbico. En este sentido, se presentan los procesos de biosíntesis para la utilización de la energía que almacenan las moléculas de ATP y se describe el transporte activo de moléculas en contra de gradientes de concentración. El transporte vesicular de proteínas, la permeabilidad de iones a través de las membranas envolventes a las paredes celulares por medio de las denominadas bombas de sodio-potasio. Posteriormente, se establecen algunos detalles acerca de los mecanismos por medio de los cuales se da la contracción muscular, haciendo referencia a la estructura de las fibras musculares. En el segundo caso, se muestra el estudio de la fisiología de la córnea, donde también se genera trabajo químico para mantener su transparencia a la luz, proveniente del exterior del ojo. Lo que conlleva a la conservación de la estructura adecuada de las células del endotelio, estroma y epitelio. Así mismo, se ilustra el requerimiento de trabajo osmótico para mantener el balance del pH en la córnea, cuando se encuentra con una deficiencia de oxígeno. En tal circunstancia se genera un flujo contra osmótico desde el humor acuoso hacia el estroma que tiende a contrarrestar el aumento de acidez.Item Design, theoretical study and correlation of the electronic and optical properties of diethynylphenylthiophene as photovoltaic materials(Elsevier B.V., 2019-09-26) Suarez, Melissa; Caicedo, Carolina; Morales, Jimmy; Flórez López, Edwin; Ávila Torres, YennyIn this work the authors reported the design of molecules with low molecular weight, which can be used in environmental applications. The systems are derived of diethynylphenylthiophene (LMWOM) coupled to phenyldiamine as spacer, forming hyper conjugated macrocycles (p-PDT, m-PDT, o-PDT, p-ZnPDT, m -ZnPDT and o-ZnPDT). Similar structures are used as sensitized materials in photovoltaic cells. The optical, geometric, electronic and photovoltaic properties was estimate using DFT, base B3LYP 6–31g (d, 2p) in Gaussian 09, software of quantum chemistry. The experimental correlation was calculated thorough of electrochemical analyses for HOMO, LUMO and GAP parameters. The results obtained to allow a rationalization or explanation of the experimental data. On the other hand, the acid Lewis effect was considered incorporating zinc(II) to lineal and macrocycle structures. The best photovoltaic parameters were described for the p-PDT molecule with PCE 26.18%, Jsc = 14.79 mA cm2 and ΔE = 2.66 eV. Also, they were also observed electronic effects in the stabilization of macrocycle, influenced by the isomer spacer. The metal ion presented three effects between lineal and macrocycle structures: To improve the electronic distribution between donor and acceptor, provides rigidity to the system favoring the optical and electronic properties and decreases GAP value. Finally, the authors correlate experimentally the method used theoretically, and it are proposed molecules with competitive properties in relationship to organic systems used as photosensitized materials, currently.Item Effect of surfactant content on rheological, thermal, morphological and surface properties of thermoplastic starch (TPS) and polylactic acid (PLA) blends(2022-10) Calambás Pulgarin, Heidy Lorena; Caicedo, Carolina; López, Edwin FlórezMiscibility in biopolymeric blends is a critical process that requires evaluation of the effect of surfactants or coupling agents under conditions similar to processing. Different mixtures in the molten state of plasticized starch and polylactic acid in the presence of a surfactant (Tween 20) at different concentrations were studied. This allowed knowing the rheological, thermal and surface behavior of the mixtures. The results of the dynamic rheological analysis showed increases in viscosity in the presence of the surfactant, in which strong interactions were produced at high shear rates that reflect possible crosslinking between the polymer chains, in addition to intermolecular interactions that were evidenced in the infrared spectrum. Likewise, the storage and loss modulus showed transitions mainly from viscous to elastic typical for thermoplastics. The thermogravimetric analysis did not show significant changes between the mixtures. However, the calorimetric analysis showed changes in the crystallinity of the mixtures, the tensoactive promotes greater freedom of movement and rearrangements in the microstructure with decrease of interface between polymers, and less compaction of the material induced by the emulsion. Analysis derived from biopolymeric films against contact with water shows significant changes. Interaction with water in short times (in the order of minutes) according to the sessile drop technique, favors hydrophilicity by increasing the concentration of Tween 20. However, interaction with water for prolonged times (in the order of hours), shows that the absorption reaches saturation in samples a stabilization in the absorption is observed. The results demonstrate that the miscibility of PLA in AS was achieved in the presence of the tween, under conventional processing conditions. The stability of the different formulations allows the production of films for packaging and biomedical applications.Item Histological Evaluation of Cassava Starch/Chicken Gelatin Membranes(2022-09) Valencia Llano, Carlos Humberto; Castro, Jorge Iván; Saavedra, Marcela; Zapata, Paula A.; Navia Porras, Diana Paola; Flórez López, Edwin; Caicedo, Carolina; Calambas, Heidy Lorena; Grande Tovar, Carlos DavidThe use of biopolymers for tissue engineering has recently gained attention due to the need for safer and highly compatible materials. Starch is one of the most used biopolymers for membrane preparation. However, incorporating other polymers into starch membranes introduces improvements, such as better thermal and mechanical resistance and increased water affinity, as we reported in our previous work. There are few reports in the literature on the biocompatibility of starch/chicken gelatin composites. We assessed the in vivo biocompatibility of the five composites (T1–T5) cassava starch/gelatin membranes with subdermal implantations in biomodels at 30, 60, and 90 days. The FT-IR spectroscopy analysis demonstrated the main functional groups for starch and chicken gelatin. At the same time, the thermal study exhibited an increase in thermal resistance for T3 and T4, with a remaining mass (~15 wt.%) at 800 °C. The microstructure analysis for the T2–T4 demonstrated evident roughness changes with porosity presence due to starch and gelatin mixture. The decrease in the starch content in the composites also decreased the gelatinization heats for T3 and T4 (195.67, 196.40 J/g, respectively). Finally, the implantation results demonstrated that the formulations exhibited differences in the degradation and resorption capacities according to the starch content, which is easily degraded by amylases. However, the histological results showed that the samples demonstrated almost complete reabsorption without a severe immune response, indicating a high in vivo biocompatibility. These results show that the cassava starch/chicken gelatin composites are promising membrane materials for tissue engineering applications.Item Microwave-assisted production of alkyl-polyglucoside from Sacha inchi oil and glucose(2023-07) Carvajal Ruiz, Uberney; Grisales Díaz, Victor Hugo; Caicedo, CarolinaEn este trabajo se han evaluado diferentes tiempos de reacción de microondas (0, 10, 20 y 30 min) para obtener un alquil poliglucósido de Sacha inchi (Plukenetia volubilis L.) y glucosa utilizando microondas a una potencia de 200 W y una temperatura de 70 °C. Las caracterizaciones de los respectivos resultados se realizaron por Espectroscopia Infrarroja Transformada de Fourier (FTIR) lo que permitió evidenciar el avance de la reacción. La cuantificación de glucosa residual se logró mediante el método colorimétrico de espectrometría mediante reacción con Antrona. El rendimiento de la reacción fue igual al 42.8%. Este estudio constituye un precedente importante para el desarrollo de tensoactivos en condiciones de reacción suaves.Item Miscibility study of thermoplastic starch/polylactic acid blends: Thermal and superficial properties(2022-10-01) Fonseca García, Abril; Osorio, Brayan Hernández; Aguirre Loredo, Rocio Yaneli; Calambas, Heidy Lorena; Caicedo, CarolinaIn this work, the miscibility of blends of thermoplastic Achira Starch (AS) and polylactic acid (PLA) was evaluated, assisted by Pluronic® F127 an amphiphilic triblock copolymer that acts as a surfactant and promotes the reduction of surface tension among AS and PLA in solution by emulsion stabilization. Different formulations of AS/PLA blends were obtained at 75:25, 50:50, and 25:75 containing 0 %, 4 %, and 8 % of Pluronic® F127, and glycerol was used as a plasticizer. Solvent casting was the method used to obtain blended polymeric films, which were characterized by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Xray diffraction (XRD), Thermogravimetric Analysis (TGA), differential scanning calorimetry (DSC) and wettability by contact angle measurements. The results demonstrate that miscibility of PLA in AS or vice versa was achieved. The stability of emulsion and posterior drying of the different formulations allows the production of films for packaging, pharmaceutical, or biomedical applications.Item Physical-mechanical behavior and water-barrier properties of biopolymers-clay nanocomposites(2021-11-01) Calambas, Heidy Lorena; Fonseca, Abril; Adames, Dayana; Aguirren Loredo, Yaneli; Caicedo, CarolinaThe preparation and characterization of biodegradable films based on starch-PVA-nanoclay by solvent casting are reported in this study. The films were prepared with a relation of 3:2 of starch:PVA and nanoclay (0.5, 1.0, and 1.5% w/v), and glycerol as plasticizer. The nanoclays before being incorporated in the filmogenic solution of starch-PVA were dispersed in two ways: by magnetic stirring and by sonication. The SEM results suggest that the sonication of nanoclay is necessary to reach a good dispersion along the polymeric matrix. FTIR results of films with 1.0 and 1.5% w/v of sonicated nanoclay suggest a strong interaction of hydrogen bond with the polymeric matrix of starch-PVA. However, the properties of WVP, tensile strength, percentage of elongation at break, and Young’s modulus improved to the film with sonicated nanoclay at 0.5% w/v, while in films with 1.0 and 1.5% w/w these properties were even worse than in film without nanoclay. Nanoclay concentrations higher than 1.0 w/v saturate the polymer matrix, affecting the physicochemical properties. Accordingly, the successful incorporation of nanoclays at 0.5% w/v into the matrix starch-PVA suggests that this film is a good candidate for use as biodegradable packaging.Item Preparation and physicochemical properties of modified corn starch–chitosan biodegradable films(2021) Jiménez Regalado, Enrique Javier; Caicedo, Carolina; Fonseca García, Abril; Rivera Vallejo, Claudia Cecilia; Aguirre Loredo, Rocio YaneliStarch is a biopolymer with enormous potential for generating new biodegradable packages due to its easy availability and low cost. However, due to its weak functional properties, limitation of its interaction with some hydroxyl groups and evaluation of blends with other polymers are necessary in order to improve its performance. Glycerol-plasticized acetylated corn starch films were developed using the casting method, and the impact of incorporating chitosan (TPS:CH) in various proportions (75:25, 50:50, and 25:75 v/v) was studied in the present research. The effect of chitosan ratios on the physical, mechanical, water-vapor barrier, and thermal properties of the film was studied. Chitosan-protonated amino groups promoted the formation of intermolecular bonds, improving tensile strength, thermal stability, hydrophobicity, water adsorption capacity, and the gas barrier of starch films. The results show that the film composed of TPS25-CH75 proved to be the best barrier to water vapor; thus, these composite films are excellent choices for developing biodegradable packaging for the food industryItem Rheological, thermal, superficial, and morphological properties of thermoplastic achira starch modified with lactic acid and oleic acid(MDPI AG, 2019-12-04) Caicedo, Carolina; Aguirre Loredo, Rocío Yaneli; Fonseca García, Abril; Hernán Ossa, Omar; Vázquez Arce, Aldo; Calambás Pulgarin, Heidy Lorena; Ávila Torres, YennyThe modification of achira starch a thermoplastic biopolymer is shown. Glycerol and sorbitol, common plasticizers, were used in the molten state with organic acids such as oleic acid and lactic acid obtaining thermodynamically more stable products. The proportion of starch:plasticizer was 70:30, and the acid agent was added in portions from 3%, 6%, and 9% by weight. These mixtures were obtained in a torque rheometer for 10 min at 130 °C. The lactic acid managed to efficiently promote the gelatinization process by increasing the available polar sites towards the surface of the material; as a result, there were lower values in the contact angle, these results were corroborated with the analysis performed by differential scanning calorimetry and X-ray diffraction. The results derived from oscillatory rheological analysis had a viscous behavior in the thermoplastic starch samples and with the presence of acids; this behavior favors the transitions from viscous to elastic. The mixture of sorbitol or glycerol with lactic acid promoted lower values of the loss module, the storage module, and the complex viscosity, which means lower residual energy in the transition of the viscous state to the elastic state; this allows the compounds to be scaled to conventional polymer transformation processes.