Carbonatación de un hormigón hibrido con alto contenido de escoria siderurgica de alto horno y su impacto en la corrosión del acero estructural

The aim of this research was to study the carbonation resistance of a blast furnace slag concrete (80% GBFS/20%OPC), with and without alkaline activation, and its influence on the corrosion of structural reinforcement. An OPC-based concrete produced under the same specifications was used as a reference material. To do this, the material was subjected to an accelerated carbonation process under controlled conditions (65% relative humidity, 1% CO2, 25°C). The half-cell potential (Ecorr), linear polarization resistance (LPR) tests showed that both concretes based on GBFS led to depassivation of the reinforcing steel at approximately 99 days, which is the time required for full carbonation of the evaluated concretes.El objetivo de esta investigación fue estudiar la resistencia a la carbonatación de un hormigón a base de escoria granulada de alto horno (80% GBFS/20%OPC), con y sin activación alcalina, y su influencia sobre la corrosión del acero estructural. Un hormigón basado en cemento portland producido con las mismas especificaciones fue usado como material de referencia. Para ello, el material fue sometido a un proceso de carbonatación acelerada bajo condiciones controladas (Humedad Relativa 65 %, 1% CO2, 25 °C). Los ensayos de potencial de media celda (Ecorr) y Resistencia a la polarización lineal (LPR) mostraron que los aceros estructurales aproximadamente a los 99 días alcanzan la despasivación en los hormigones basados en escoria, coincide este tiempo con el requerido para la completa carbonatación de los hormigones evaluados

Toxicidad sub crónica y actividad analgésica in vivo del extracto clorofórmico de las hojas de Calea urticifolia (Juanislama

Introduction: The population uses medicinal plants indiscriminately to treat diseases, with the believe that they are safe and lack adverse effects. Objective: To determine the in vivo toxicological and analgesic effect of the chloroform extract of Calea urticifolia leaves. Methodology: The toxicological study was performed using a 90- day sub-chronic toxicity test in NIH mice, at repeated and continuous doses. . Blood biochemistry, hematology and histopathological examination of organs were performed. The analgesic activity was evaluated in vivo using a model of abdominal contortions. Results: The administration of the plant extract caused the appearance of clinical signs of toxicity, alterations in hematic parameters and blood biochemistry, as well as histological alterations in some of organs. The analgesic activity at 100 mg/kg was similar to the Indomethacin drug. Conclusion: Despite the proven analgesic activity, according to the observed toxicological effects in this study, the prolonged use of Calea urticifolia leaves is not recommended for the treatment of diseasesIntroducción: La población utiliza la medicina a base de hierbas de forma indiscriminada basándose en la creencia de que las plantas medicinales carecen de efectos adversos. Objetivo: Determinar in vivo el efecto toxicológico y analgésico del extracto clorofórmico de las hojas de Calea urticifolia. Metodología: El estudio toxicológico fue realizado mediante la prueba de toxicidad subcrónica de 90 días, a dosis repetidas y continuas en ratones NIH. Se realizaron análisis de bioquímica sanguínea, hematología y el examen histopatológico de órganos. La actividad analgésica fue evaluada con el modelo in vivo de contorsiones abdominales. Resultados: La administración del extracto vegetal provocó la aparición de signos clínicos de toxicidad, alteraciones en los parámetros hematólogos y bioquímica sanguínea, además alteraciones histológicas en algunos de los órganos. La actividad analgésica a 100 mg/kg resultó comparable con el fármaco indometacina. Conclusión: Pese a la actividad analgésica demostrada, y de acuerdo a los efectos toxicológicos encontrados, no se recomienda el uso prolongado de las hojas de Calea urticifolia, para el tratamiento de enfermedade

Effect of extrusion and autoclaving on the biological potential of proteins and naturally-occurring peptides from common beans: Antioxidant and vasorelaxant properties

Aiming to understand the impact of hardening on the biological potential of bean protein and peptides, we evaluated the antioxidant and vasorelaxant properties of common beans after and before hardening. It was also evaluated the effect of extrusion and autoclaving in the biological potential of hardened beans. In general, hardening caused a reduction from 13.5 to 39.6% on the antioxidant activity of the peptide-rich fractions. On the other hand, hardening did not strongly interfere with the vascular reactivity in thoracic aorta rings, being observed maximal relation varying from 801% to 84.7%. The thermal treatment caused a general increase in the antioxidant and vasorelaxant potential of these fractions, being observed EC50 values ranging from 0.22 mg mL -1 to 0.26 mg mL -1. We can conclude that hardening did not seem to affect definitively the bioactivity of the obtained peptide-rich fractions. Finally, this study allows suggesting practical applications of extrusion as a thermal process in the production of functional food ingredients, and as ready-to-eat products presenting nutraceutical potential. In addition, autoclaving can be used as a pre-treatment of the hardened grains aiming to use them as whole grains with potentialized benefits for human health

Diseño y construcción de un deshidratador solar de frutos tropicales

The depletion of fossil resources and environmentalimplications associated with its use has led to interestin the use of renewable resources. Among these, solarenergy has great potential in the process of obtainingenergy and heat. Specifically, in the development offruit dehydration processes. This paper describes thedesign and construction of a solar dehydration equipmentinduced flow. The equipment obtained as a resultof this study allows for the development of thedehydration process in tropical fruits of different physicaland organoleptic characteristics. First, the studyfocused on the selection of the equipment deploymentpoint and selecting the constructive disposition.Subsequently, it was focused on the design, dimensioningand construction of the equipment. Finally,dehydration tests were performed; the results arecompared with the results of traditional dehydrationequipment and with data obtained from the use ofmathematical models used for simulating the process.The results provide evidence of differences of 20 %in processing times using solar energy compared toenergy derived from fossil fuel. In the same way, it isestablished that the modified Page model is the onethat best fits the data obtained from the dehydrationprocess developed in this study. Design innovationsdeveloped in this study allow obtaining dehydratedfruits evenly and reducing CO2.El agotamiento de recursos fósiles y las implicacionesambientales asociadas a su uso han originadointerés en recursos renovables. Dentro de éstos, laenergía solar presenta gran potencial en los procesosde obtención de energía y calor, específicamente,en el desarrollo de procesos de deshidrataciónde frutos. Este artículo describe el diseño y construcciónde un equipo de deshidratación solar deflujo inducido. Los instrumentos obtenidos comoresultado de este estudio permiten el desarrollo delproceso de deshidratación en frutos tropicales dediferentes características físicas y organolépticas.En primer lugar, el estudio se centra en la seleccióndel punto de implementación del equipo y la selecciónde la disposición constructiva del mismo. Posteriormente,se realiza el diseño, dimensionamientoy construcción de los materiales. Finalmente, serealizan pruebas de deshidratación; los resultadosse comparan con datos obtenidos en equipos dedeshidratación tradicionales y con datos de modelosmatemáticos empleados en dichos procesos.Los resultados evidencian diferencias de un 20 %en los tiempos de procesamiento, al emplear energíasolar en comparación con energía obtenida derecursos fósiles; de la misma forma, se estableceque el modelo de Page modificado es el que mejorse ajusta a los datos obtenidos del proceso de deshidratacióndesarrollado en este estudio. Las inno-vaciones de diseño desarrolladas en esta investigaciónpermiten la obtención de frutos deshidratadosde manera homogénea y la reducción de emisionesde CO2

Mobility and postural limitations perceived by transtibial amputees undertaking agricultural activities: a qualitative study

AbstractPurpose In Colombia, 98% of landmines occur in rural areas, where the main victims of amputation are farmers. The challenges these amputees face in their agricultural work remain unknown. The aim of this study is to determine the mobility and postural limitations these farmers face in carrying out their daily activities.Method Forty-nine participants meeting the following criteria were interviewed: transtibial amputee, 18 years and over, performs agricultural labour and wears the prosthesis daily. Subsequently, the interview transcripts were subjected to a content conventional analysis and responses were organized according to the abstraction process to identify categories and subcategories of the problems.Results Main problems reported were walking on sloping, uneven and wet terrain, problems associated with the stump skin, squatting, kneeling, using vehicles or animals for transportation and carrying objects over 30 kg. Postures such as sitting, running, jumping, and standing on tiptoes were mentioned less frequently.Conclusions In conclusion, the prostheses worn by transtibial amputee farmers are not suitable for working on sloping and uneven terrain, nor for performing postures such as kneeling or squatting. These postures are very common in agricultural and livestock tasks in countries with mountainous areas such as Latin American countries. The recognition of problems reported by farmers transtibial amputees, may help to improve the design of prostheses so that they meet the needs of this population and decrease secondary injuries associated with prosthetic use. This information is useful to identify compensatory postures that facilitate prosthetic adaptation and rehabilitation for amputees

Source area evolution and thermal record of an Early Cretaceous back-arc basin along the northwesternmost Colombian Andes

Identifying the provenance signature and geodynamic setting on which sedimentary basins at convergent margins grow is challenging since they result from coupled erosional and tectonic processes, which shape the evolution of source areas and the stress regime. The Early Cretaceous evolution of the northern Andes of Colombia is characterized by extensional tectonics and the subsequent formation of a marginal basin. The Abejorral Formation and coeval volcano-sedimentary rocks are exposed along the western flank and axis of the Central Cordillera. They comprise an Early Cretaceous transgressive sequence initially accumulated in fluvial deltaic environments, which switched towards a deep-marine setting, and are interpreted as the infilling record of a marginal back-arc basin. Available provenance data suggest that Permian-Triassic metamorphic and less abundant Jurassic magmatic rocks forming the basement of the Central Cordillera sourced the Abejorral Formation. New detailed volcanic and metamorphic lithics analyses, conventional and varietal study of heavy minerals, detrital rutile mineral chemistry, allowed us to document changes in the source areas defined by the progressive appearance of both higher-grade and more distal low-grade metamorphic sources, which switched from pelitic to dominantly mafic in composition. Crystallochemical indexes of clay minerals of fine-grained rocks of the Abejorral Formation suggest that samples located close to the Romeral Fault System show characteristics of low-medium P-T low-grade metamorphism, whereas rocks located farther to the northeast preserve primary diagenetic features, which suggest a high heat-flow accumulation setting. We interpret that the Abejorral Formation records the progressive unroofing of the Central Cordillera basement that was being rapidly exhumed, as well as the incorporation of distal subduction-related metamorphic complexes to the west in response either to the widening of extensional front or the reactivation of fault structures on the oceanward margin of the basin. Although the deformational record of the Abejorral Formation would have resulted from over-imposed episodes, our new geochronological constraints suggest that this sedimentary sequence must have been deformed before the Paleocene due to the presence of arc-related intrusive non-deformed magmatic rocks with a crystallization age of ca. 60 Ma.Fil: León, S.. Universidad Nacional de Colombia; Colombia. Smithsonian Tropical Research Institute; PanamáFil: Cardona, A.. Universidad Nacional de Colombia; ColombiaFil: Mejía, D.. Universidad Nacional de Colombia; ColombiaFil: Botello, G. E.. Universidad Nacional de Colombia; ColombiaFil: Villa, V.. Universidad Nacional de Colombia; ColombiaFil: Collo, Gilda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Valencia, V.. Washington State University; Estados UnidosFil: Zapata, S.. Universita Zu Berlin. Universita Postdam; AlemaniaFil: Avellaneda-Jiménez, D.S.. Universidad Nacional de Colombia; Colombi

Hepatotoxicidad por antituberculosos en el Hospital Universitario San Vicente de Paúl, Medellín, 2005-2007

OBJETIVO: determinar la incidencia de hepatotoxicidad por medicamentos antituberculosos, en pacientes tratados en el Hospital Universitario San Vicente de Paúl, de Medellín, en el período comprendido entre enero de 2005 y diciembre de 2007. MÉTODOS: estudio retrospectivo de toda la población con diagnóstico de tuberculosis en el período en mención. RESULTADOS: se incluyeron 224 historias y se encontró una incidencia de hepatotoxicidad de 21%, mayor que la reportada en la literatura. El principal factor de riesgo encontrado para el desarrollo de la hepatotoxicidad fue el VIH; en contraste con otros estudios, factores como edad, sexo y raza no fueron de riesgo para el desarrollo de la misma. Encontramos también que no hubo acuerdo en cuanto a la conducta para seguir una vez diagnosticada la hepatotoxicidad; solo en el 54% de los casos se suspendió el tratamiento y se hizo reintroducción escalonada. CONCLUSIÓN: el estudio evidencia la necesidad de programas de farmacovigilancia que busquen activamente esta complicación y desarrollen guías para unificar conceptos y protocolos de tratamiento