Artículos científicos

URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/14823

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Mostrando 1 - 4 de 4

Biosensor based on the directly enzyme immobilization into a gold nanotriangles/conductive polymer biocompatible coat for electrochemical detection of Chlorpyrifos in water
(Wiley Periodicals, Inc., 2019) Ramírez Sánchez, Karla; Alvarado Hidalgo, Fernando; Zamora-Sequeira, Roy; Sáenz-Arce, Giovanni; Rojas Carrillo, Oscar; Avendaño Soto, Esteban Damian; Ruepert, Clemens; Mena, Freylan; Starbird-Perez, Ricardo
Abstract. Organic conductive polymers have been widely used as active layers in bioelectronic devices. In this work, a novel approach to entrap enzymes directly into the conductive active layer is described, using a polysaccharide as a surfactant. The surfactant allowed the electropolymerization from a micellar media and it acted as a doping agent in the conductive polymer. Gold nanotriangles were added to the matrix in order to enhance the enzymatic product quantification. The composition and oxidation state of the biocompatible conductive layer were confirmed by infrared spectrophotometric and Raman studies. Meanwhile, the gold nanotriangles presence, distribution and electrochemical activity were studied by transmission electron microscopy, atomic force microscopy, dynamic light scattering and cyclic voltammetry techniques. The inhibition of the enzyme, due to the presence of pesticides, was used to electrochemically quantify their concentration in real water samples. The concentration was confirmed by gas and liquid chromatography. Therefore, this novel composite active layer allows building a biosensor with suitable performance for an early warning in environmental control, especially in countries highly impacted by agricultural activities.
Una contribución a la ecología del Golfo de Nicoya
(Universidad Nacional (Costa Rica), 1998) León Coto, Sandra; Kress, Nurit; Brenes Rodríguez, Carlos; Brenner, Steve
Las tendencias de los últimos 20 años indican a nivel mundial un aumento de la contaminación marina, una aceleración de la destrucción de los hábitats marino-costeros y, en muchas áreas una menor captura de especies marinas afectadas por la pesca excesiva y la contaminación. Se estudiaron (1995-1996) los patrones de transporte de nutrientes, la estacionalidad del oxígeno y de los nutrientes disueltos; la escorrentía de los principales ríos, su aporte de nutrientes y su contribución sobre los niveles de clorofila-a (como aproximación a biomasa de fitoplankton); distribución de metales pesados en los sedimentos y el contenido de metales de la biota como posibles bioindicadores; el modelaje hidrodinámico de los procesos de transporte y circulación de las aguas en el Golfo de Nicoya, así como el modelaje parcial de la dinámica de los nutrientes.
Kinetics of anaerobic degradation of screened dairy manure by upflow fixed bed digesters: Effect of natural zeolite addition
(Taylor & Francis, 2009) Nikolaeva, S.; Sánchez, E.; Borja, R.; Raposo, F; Colmenarejo, M. F.; Montalvo, S.; Jiménez-Rodríguez, Antonia-Mercedes
The effect of the hydraulic retention time (HRT) on the performance of two up-flow anaerobic fixed bed digesters (UFAFBDs) packed with waste tire rubber (D1) and waste tire rubber and zeolite (D2) as micro-organism immobilization supports was studied. It was found that a first-order kinetic model described well the experimental results obtained. The kinetic constants for COD, BOD5, total solids (TS) and volatile solids (VS) removal were determined to be higher in digester D2 than in digester D1 or control. Specifically, they were 0.28 ± 0.01, 0.32 ± 0.02, 0.16 ± 0.01 and 0.24 ± 0.01 d- 1 respectively for D1 and 0.33 ± 0.02, 0.40 ± 0.02, 0.21 ± 0.01 and 0.28 ± 0.01 d- 1 respectively for D2. This was significant at the 95% confidence level. In addition, the first-order model was also adequate for assessing the effect of the HRT on the removal efficiency and methane production. Maximum methane yield and the first-order constant for methane production were determined and the results obtained were comparable with those obtained by other authors but operating at higher HRTs. Maximum methane yields and the kinetic constant for methane production were 11.1% and 29.4% higher in digester D2 than in D1. Copyright © Taylor & Francis Group, LLC.
Síntesis y Caracterización de Celulosa Amorfa a partir de Triacetato de Celulosa
(Sociedad Química del Perú (Perú), 2014) Jose-Roberto, Vega-Baudrit; Sibaja B., María; Nikolaeva, Svetlana; Rivera A., Andrea
Se realizó un estudio para la obtención y caracterización de celulosa amorfa a partir de triacetato de celulosa. Para caracterizar el material obtenido, se determinó el grado de cristalinidad mediante la difractometría de rayos X, además de la espectroscopía de infrarrojo FTIR.

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Examinando Artículos científicos por browse.metadata.procedence "Departamento de Física"