Cambio actitudinal de estudiantes de octavo grado hacia el aprendizaje de interacciones biológicas mediante la resolución de problemas

Se presenta aquí una experiencia pedagógica en enseñanza de la biología, desarrollada en el espacio académico de Aula experimental de la Universidad Distrital Francisco José de Caldas, con 28 estudiantes de grado 8vo del Colegio La Candelaria, sede la Concordia, en la ciudad de Bogotá (Colombia) con un rango de edades entre los 12 y los 17 años, se escogen tres estudiantes, tomando como eje conceptual las interacciones biológicas. Este trabajo se realizó en las etapas de planificación, diseño y implementación de la unidad didáctica “Preguntando ando, con el ecosistema interactuando” la cual se centró en el enfoque de enseñanza por resolución de problemas. En la finalización de este trabajo se encontró un cambio actitudinal de los estudiantes con respecto al aprendizaje del eje conceptual, teniendo como referente los componentes actitudinales expuestos por Vilches y Furió (1997)

Studies of mass transfer coefficients in denitrifying biofilms

Mass transfer coefficients within denitrifying biofilms were determined with an inert compound (LiCl) using two different flow conditions in a membrane flow cell and feeding an easily degradable substrate. The experiments were made until the biofilm reached steady state. The results obtained from the biofilm mass transfer experiments show that the biofilms grown under these two different conditions reach similar values in the steady state. However, the mass transport was higher during biofilm formation, for the biofilm developed under higher upflow velocity.Comissão Europeia, TMR program (project BioToBio); Spanish CICYT (project AMB 98-0288)

Use of a membrane flow cell to measure average mass transfer coefficients in denitrifying biofilms

Average mass transfer coefficients within denitrifying biofilms were determined during biofilm growth with an inert compound (LiCl) in a membrane flow cell at different flow conditions, until the biofilm reached (pseudo-) steady state. Similar values were obtained for the steady-state mass transfer coefficients of LiCl within the different biofilms. However, those coefficients were higher during the transient period of biofilm growth for the biofilm developed under the highest upflow velocity.Xunta de Galicia, project BioToBi

A technique using a membrane flow cell to determine average mass transfer coefficients and tortuosity factors in biofilms

Average mass transfer coefficients of an inert compound (LiCl) within denitrifying biofilms were monitored during biofilm growth in a membrane flow cell under different flow conditions, until the biofilm reached (pseudo-) steady state. Average effective diffusivities were found to increase with the decrease in tortuosity factors of the biofilm matrix. The lowest tortuosity factor corresponded to the biofilm formed under the highest liquid velocity.União Europeia - BioToBio - ERBFMRXCT97-0114. Centro de Investigación Científica y Tecnológica (CICYT) - AMB 98-0288, PR404E 2000/6-

Promising Impregnated Mn-based Oxygen Carriers for Chemical Looping Combustion of Gaseous Fuels

Promising impregnated oxygen carriers, based on copper and iron, have been previously developed for CLC with gaseous fuels (CH4, syngas, LHC). Recently, because of its low cost and environmental compatibility, Mn-based oxygen carriers are now being considered as an attractive option for chemical-looping combustion (CLC) applications. In this work, a screening of different commercial supports in fluidizable particle size for impregnated Mn-based materials has been carried out. Different oxygen carriers have been prepared by incipient impregnation on ZrO2, and CaAl2O4, and evaluated with respect to their mechanical resistance, fuel gas reactivity and fluidization properties such as agglomeration and attrition rate. In a first step, particles showing high enough crushing strength values were selected for the reactivity investigation. The redox reactivity was evaluated through TGA experiments at suitable temperatures for the CLC process (i.e. 850-950 °C) using H2, CO and CH4. Multi cycle redox analysis and full physical and chemical characterization was also performed. In a second step, materials with high enough reactivity were prepared for fluidized bed evaluation. A batch fluidized bed installation with continuous gaseous fuel feed was used to analyze the product gas distribution during reduction and oxidation reactions at different operation temperatures, and agglomeration and attrition behavior of the selected materials. Results showed that an oxygen carrier impregnated using ZrO2 as support, had high enough reactivity and low attrition rate. Therefore, this material can be selected as a candidate for the development of CLC with syngas with promising results

Climate change implications for the distribution of the babesiosis and anaplasmosis tick vector, Rhipicephalus (Boophilus) microplus

This work is licensed under a Creative Commons Attribution 4.0 International License.Climate change ranks among the most important issues globally, affecting geographic distributions of vectors and pathogens, and inducing losses in livestock production among many other damaging effects. We characterized the potential geographic distribution of the ticks Rhipicephalus (Boophilus) microplus, an important vector of babesiosis and anaplasmosis globally. We evaluated potential geographic shifts in suitability patterns for this species in two periods (2050 and 2070) and under two emissions scenarios (RCPs 4.5 and 8.5). Our results anticipate increases in suitability worldwide, particularly in the highest production areas for cattle. The Indo-Malayan region resulted in the highest cattle exposure under both climate change projections (2050), with increases in suitability of > 30%. This study illustrates how ecological niche modeling can be used to explore probable effects of climate change on disease vectors, and the possible consequences on economic dimensions.Fulbright Visiting Scholar Program-Senior ScholarConselho Nacional de Desenvolvimento Científico e Tecnológico (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Tumor fusocelular hialinizante con rosetas gigantes. Reporte de un caso

RESUMEN Introducción: El tumor fusocelular hialinizante con rosetas gigantes es una neoplasia constituida por dos componentes histológicos, uno celular con elementos fusiformes, y el segundo representado por islas bien delimitadas casi acelulares, llenas de material hialino, rodeadas de células redondas u ovales, las cuales muestran un perfil inmunohistoquímico inusual, e histogénesis incierta.Objetivo: Instruir a los patólogos y clínicos sobre este tumor, su forma de presentación y diagnósticos diferenciales.Metodología y resultados: Se presenta el caso de una mujer de 42 años con masa ubicada en región inguinal, de crecimiento progresivo (1 año), que se reseca quirúrgicamente anatomía patológica informó un tumor fusocelular hialinizante con rosetas gigantes, según hallazgos morfológicos e inmuno histoquímicos, en correlación con su localización y cuadro clínico.Conclusión: Se hace necesario ampliar el conocimiento sobre esta entidad y de esta forma obtener una adecuada evaluación de sus criterios pronósticos histológicos, comportamiento clínico y tratamiento. Salud UIS 2010; 42:     Palabras clave: Tumor fusocelular hialinizante con rosetas gigantes, fibrosarcoma, sarcoma fibromixoide de bajo grado, inmunohistoquímica   ABSTRACT Introduction: The hyalinizing spindle cell tumor with giant rosettes is a neoplasia characterized by both histologic components, one of which is cellular, with spindle-shaped elements and the second represented by well defined almost acellular islands filled with hyaline material surrounded by round to oval cells, which shows an unusual immunohistochemical profile and uncertain histogenesis.Objective: Educate pathologists and clinicians about this tumor, its presentation and differential diagnosis.Methods and results: A case of a 42 year old woman with a mass located in the inguinal region, with progressive growth (1 year), surgically resected and histopathology reported as Hyalinizing spindle cell tumor with giant rosettes according to morphological, immunohistochemical findings correlates with its location and clinical.Conclusion: It is necessary to expand awareness about this condition and thus obtain a proper assessment of histological prognostic criteria, clinical behavior and treatment. Salud UIS 2010; 42:   Keywords: Hyalinizing spindle cell tumor with giant rosettes, grade fibromyxoid sarcoma, Immunohistochemistr

Tumor fusocelular hialinizante con rosetas gigantes. Reporte de un caso

RESUMEN Introducción: El tumor fusocelular hialinizante con rosetas gigantes es una neoplasia constituida por dos componentes histológicos, uno celular con elementos fusiformes, y el segundo representado por islas bien delimitadas casi acelulares, llenas de material hialino, rodeadas de células redondas u ovales, las cuales muestran un perfil inmunohistoquímico inusual, e histogénesis incierta.Objetivo: Instruir a los patólogos y clínicos sobre este tumor, su forma de presentación y diagnósticos diferenciales.Metodología y resultados: Se presenta el caso de una mujer de 42 años con masa ubicada en región inguinal, de crecimiento progresivo (1 año), que se reseca quirúrgicamente anatomía patológica informó un tumor fusocelular hialinizante con rosetas gigantes, según hallazgos morfológicos e inmuno histoquímicos, en correlación con su localización y cuadro clínico.Conclusión: Se hace necesario ampliar el conocimiento sobre esta entidad y de esta forma obtener una adecuada evaluación de sus criterios pronósticos histológicos, comportamiento clínico y tratamiento. Salud UIS 2010; 42:     Palabras clave: Tumor fusocelular hialinizante con rosetas gigantes, fibrosarcoma, sarcoma fibromixoide de bajo grado, inmunohistoquímica   ABSTRACT Introduction: The hyalinizing spindle cell tumor with giant rosettes is a neoplasia characterized by both histologic components, one of which is cellular, with spindle-shaped elements and the second represented by well defined almost acellular islands filled with hyaline material surrounded by round to oval cells, which shows an unusual immunohistochemical profile and uncertain histogenesis.Objective: Educate pathologists and clinicians about this tumor, its presentation and differential diagnosis.Methods and results: A case of a 42 year old woman with a mass located in the inguinal region, with progressive growth (1 year), surgically resected and histopathology reported as Hyalinizing spindle cell tumor with giant rosettes according to morphological, immunohistochemical findings correlates with its location and clinical.Conclusion: It is necessary to expand awareness about this condition and thus obtain a proper assessment of histological prognostic criteria, clinical behavior and treatment. Salud UIS 2010; 42:   Keywords: Hyalinizing spindle cell tumor with giant rosettes, grade fibromyxoid sarcoma, Immunohistochemistr