Estrategias discursivas para la construcción colaborativa del conocimiento en entornos virtuales de aprendizaje

El objetivo del presente trabajo es tratar de identificar algunas estrategias discursivas que puedan asociarse de manera específica a y al mismo tiempo, configurar las diversas fases de construcción colaborativa del conocimiento desarrolladas por grupos de estudiantes universitarios que resuelven tareas de elaboración conjunta de productos escritos en un entorno de aprendizaje mediado por ordenador. Para ello, se ha realizado un estudio de casos en situación natural, en dos situaciones o contextos instruccionales distintos, correspondientes a sendas asignaturas del ámbito de la Psicología de la Educación. En cada situación, se han seguido tres pequeños grupos de estudiantes, y se han analizado las tareas correspondientes a dos secuencias didácticas completas y consecutivas. Como resultado, se ha podido identificar un amplio conjunto de estrategias discursivas típicas de cada una de las fases de construcción colaborativa del conocimiento consideradas. Estas estrategias remiten a formas de uso del lenguaje mediante las cuales los miembros del grupo consiguen, en cada caso, alcanzar el nivel de intersubjetividad y el grado de construcción de conocimiento compartido propio de la fase.

Enriquecimiento, disponibilidad y contaminación de metales traza (Cd, Cu, Pb y Zn) en sedimentos de lagunas urbanas de Concepción-Chile

Trace metals (Cd, Cu, Pb and Zn) enrichment, availability and contamination in superficial sediments of three interconnected urban lagoons localized in Concepción-Chile, were evaluated. According to the results of geochemical fracctionation analysis, Cu and Pb are rather associated with oxi-hydroxides, Cd is associated with exchangeable and carbonates fraction, while Zn is mainly associated with organic, oxi-hydroxides and residual fraction. The estimation of the availability percentages indicate that Cu is the most mobile metal and the less mobile is the Cd. An evaluation of the geo-accumulation index and urban industrial pollution allowed to classify the studied zone as moderately to highly contaminated.

ELETRODOS DE FTO MODIFICADOS POR ELETRODEPOSIÇÃO DIRETA DE OURO: PRODUÇÃO, CARACTERIZAÇÃO E APLICAÇÃO COMO SENSOR ELETROQUÍMICO

Chemically modified electrodes have been studied to obtain new and better electrochemical sensors. Transparent conductive oxides, such as fluorine-doped tin-oxide (FTO), shows electrical conductivity comparable to metals and are potential candidates for new sensors. In this work, FTO was modified by gold electrodeposition from chlorine-auric acid solution using cyclic voltammetry (CV) technique. A set of different materials were produced, varying the scan number. Scanning electron microscopy and electrochemical impedance spectroscopy were performed for the characterization of electrodes surfaces. From this analysis was possible to observe the resistive, capacitive and difusional aspects from all kind of modified electrodes produced, establishing a relationship between this parameters and the scan number. The electrode with 100 scans of CV presented better characteristics for an electrochemical sensor; it has the lowest global impedance and rising of capacitive behavior (related to electrical double layer formation) at lower frequencies. This electrode was tested for paracetamol and caffeine detection. The results showed a high specificity, decreased oxidation potential (0.58 V and 0.97 Vvs. SCE, for paracetamol and caffeine, respectively) and low detection limits (0.82 and 0.052 µmol L-1).

Improvement of bovine ß-lactoglobulin production and secretion by Lactococcus lactis

The stabilizing effects of staphylococcal nuclease (Nuc) and of a synthetic propeptide (LEISSTCDA, hereafter called LEISS) on the production of a model food allergen, bovine ß-lactoglobulin (BLG), in Lactococcus lactis were investigated. The fusion of Nuc to BLG (Nuc-BLG) results in higher production and secretion of the hybrid protein. When LEISS was fused to BLG, the production of the resulting protein LEISS-BLG was only slightly improved compared to the one obtained with Nuc-BLG. However, the secretion of LEISS-BLG was dramatically enhanced (~10- and 4-fold higher than BLG and Nuc-BLG, respectively). Finally, the fusion of LEISS to Nuc-BLG resulting in the protein LEISS-Nuc-BLG led to the highest production of the hybrid protein, estimated at ~8 µg/ml (~2-fold higher than Nuc-BLG). In conclusion, the fusions described here led to the improvement of the production and secretion of BLG. These tools will be used to modulate the immune response against BLG via delivery of recombinant lactococci at the mucosal level, in a mouse model of cow's milk allergy.

Effects of filtration methods on the neutralization yield of crude marine fish oil

The evaluation of filtration methods on the yield and oleochemicals characteristics on the crude fish oil from the soapstock of marine fish for purposes of nutrition has been conducted in this work. The analytical properties of the crude and the neutralized oil with three excesses of sodium hydroxide (NaOH, 20%, 40% and 60%) were carried out on two different ways with organza and the “glass wool”. The neutralization of the oil brought about a notable improvement in the analytical properties of the oil. Thus, it leads to a high quality fish oil in terms of taste, colour, odours, shelf life and market value. Based on the improved characteristics of the oil, it could be suitable for applications in pharmaceutical and food industries.

Characterization of a hydrolyzed oil obtained from fish waste for nutraceutical application

The fish industry generates high volume of waste from fish oil that can have the extraction of its lipids used as nutraceuticals and foods. The objective of this study was to produce unsaturated fatty acids from industrialized fish oil by means of a differentiated hydrolysis process. The samples used were crude fish oil obtained from Campestre industry and characterized through physical-chemical parameters, according to AOCS: acidity, peroxide, saponification, iodine and percentage of free fatty acids and also obtained the fatty acid profile through derivatization method for gas chromatography. The results obtained for the oleochemical indices for refined oil were similar to the data found on the literature. The content of polyunsaturated fatty acids (PUFA) was found of 32,78%, with 9,12% of docosahexaenoic (DHA) and 10,36% of eicosapentaenoic (EPA), regarding monounsaturated fatty acids (MUFA) content was of 30,59% in the hydrolyzed fish oil in relation to refined (20,06%). Thus, it can be concluded that the hydrolysis process used for oils from fish-waste was satisfactory on the production of absolute yield of lipids in the process and significant preservation on the percentages of EPA and DHA, interesting on the production of nutraceuticals and nutrition of aquatic animals, including shrimp in captivity.

Encuesta social de Bogotá en comparación con Bucaramanga y Cali, 2005

Gestión del conocimiento

Balance de la economía bogotana en el 2002 y primer semestre de 2003

Gestión del conocimiento

Evaluación de los cambios en la calidad de vida en Bogotá durante el 2008

Gestión del conocimiento

Avances y seguimientos a los compromisos del comité empresarial de Apoyo: Localidad de Ciudad Bolivar (19) Abril 2012.

Gestión del Conocimiento

Avances y seguimientos a los compromisos del comité empresarial de Apoyo: Localidad Engativá (10) Marzo 2012.

Gestión del Conocimiento

Avances y seguimientos a los compromisos del comité empresarial de Apoyo: Localidad de Kennedy (8) Abril 2012.

Gestión del Conocimiento

Avances y seguimientos a los compromisos del comité empresarial de Apoyo: Localidad de Ciudad Bolivar (19) Marzo 2012.

Gestión del Conocimiento

Avances y seguimientos a los compromisos del comité empresarial de Apoyo: Localidad de Kennedy (8) Marzo 2012.

Gestión del Conocimiento

Balance de la economía bogotana en el 2005 y primer semestre de 2006

Gestión del conocimiento