Preparation And Characterization Of Cassiterite (SNO2) And Its Application In The Hydrogenation Of Methyl Esters.

Tin oxide (IV) or cassiterite obtained by the controlled precipitation method was characterized by different physical and chemical techniques such as TEM, surface area, XRD and RTP for the determination of the morphology, particle size distribution and reduction temperature of the system and then, a pure catalyst and doped with tin (Sn) and nickel (Ni) is employed in the hydrogenation of methyl esters from palm oil. Monitoring the reaction was carried out by gas chromatography and it was found that the Sn-doped system showed a higher activity towards hydrogenation. The products obtained during and after the reaction were analyzed by FT-IR. We found that the hydrogenation of double bonds of the carbon chain was the main reaction, but there were also products resulting from isomerization and surprisingly a small fraction of fatty alcohols with tin-based catalyst Sn/SnO2

Reproductive biology of parona signata (Actinopterygii: Carangidae), a valuable economic resource, in the coastal area of mar del plata, buenos aires, argentina

Se estudió la biología reproductiva y el ciclo de vida de la palometa pintada, Parona signata en Mar del Plata (38°00’S 57°33’O). Las muestras fueron obtenidas mensualmente desde enero de 2018, hasta febrero de 2019, provenientes de la pesca artesanal y/o de la flota comercial de la localidad Mar del Plata. Además, se llevó a cabo un análisis histológico y se estimaron los principales parámetros reproductivos tales como: la fecundidad, análisis de la distribución de la frecuencia de diámetros ovocitarios e índice gonadosomático (GSI) mensual. Tanto el análisis macroscópico como el microscópico permitieron afirmar que en los meses de marzo y noviembre existe actividad reproductiva. Se encontraron hembras en puesta, las cuales presentaron ovocitos hidratados en los cortes histológicos. Ambos, los análisis histológicos y de distribución de la frecuencia de diámetros oocitarios mostraron la presencia de todas las fases de maduración oocitaria en ovarios correspondientes a la sub-fase de desove activo, indicando que P. signata es un desovante parcial con fecundidad anual indeterminada. La fecundidad parcial osciló entre 36.426 y 126.035 oocitos hidratados/hembra. La fecundidad relativa varió entre 42 y 150 ovocitos por gramo de hembra libre de ovario.The reproductive biology and life cycle of Parona leatherjacket, Parona signata (Carangiformes), present in Mar del Plata (38°00′S 57°33′W) coast, was studied. Samples were obtained monthly since January 2018 to February 2019 from the artisanal fishermen and the commercial fleet of Mar del Plata. A histological analysis was carried out and the main biologic-reproductive parameters were estimated: fecundity, oocyte frequency distribution and gonadosomatic index (GSI). Both the macroscopic and microscopic analyses showed reproductive activity in March and November. Mature females were recorded, which showed hydrated oocytes, as was evidenced by the histological procedures. Both, the histological and the oocyte diameter distribution analyses showed the presence of all oocyte maturation stages in ovaries in active-spawning subphase, indicating that P. signata is a multiple spawner with indeterminate annual fecundity. Batch fecundity ranged between 36,426 and 126,035 hydrated oocytes/ female. Relative fecundity ranged between 42 and 150 oocytes/ g female ovary free.Fil: Bianchi, Santiago Julián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: González Castro, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Desarrollo y evaluación de un dispositivo háptico de 5 grados de libertad a partir de dos sistemas novint falcon de 3 grados de libertad

El presente proyecto tiene como objeto el desarrollo y la evaluación de un dispositivo hápico con 5 grados de libertad (GDL) para el mejoramiento e habilidades motrices. El sistema general se divide en tres grandes partes, la primera es el diseño del dispositivo mecánico, el cual une los dos dispositivos Novint Falcon, la segunda es el prototipo de software que controla el sistema y sirve para poner en prueba el sistema desarrollado, la última parte es la evaluación del proyecto mediante un protocolo experimental que permite comparar el sistema de 3 GDL con el 5 GDL. La idea del proyecto surge de la curiosidad de unir dos dispositivos Novint Falcon para obtener un sistema con mayor número de grado de libertad, con el fin de realizar tareas de simulación más complejas con menos limitaciones de movimientoPregrad

Diseño e implementación de un sistema de telemetría para el monitoreo de un sistema de generación de energía solar fotovoltaico

Este proyecto de grado se realizó con el fin de apoyar a la Facultad de Tecnología y el programa de Tecnología Mecánica de la Universidad Tecnológica de Pereira, cuyos estudiantes y profesores llevaron a cabo la instalación de un sistema de generación de energía solar en la Fundación Kyrios. La idea principal del proyecto es desarrollar una herramienta que fortalezca la investigación y el desarrollo de este tipo de proyectos y que permita el monitoreo permanente de las variables involucradas en el sistema de generación de energía. Este sistema consiste en capturar a través de dispositivos electrónicos y sensores los valores de corriente y voltaje involucrados en el proceso de generación de energía solar fotovoltaica, convertir esta información en datos digitales para ser almacenados y publicados por medio de una plataforma tecnológica web. El monitoreo a través de internet permite que el proceso de generación de energía solar fotovoltaica pueda ser observado desde cualquier computador o dispositivo móvil que cuente con acceso a internet

Un Análisis del Ciclo Económico en Competencia Imperfecta

El objetivo de este artículo, que hace parte de un estudio más extenso, es analizar el tema de las fluctuaciones del producto en un escenario de competencia imperfecta a la luz de los hechos estilizados. Se conclue que estas se pueden originar por shocks de oferta o demanda, o simplemente por el ajuste de la economía ante desbalances en los mercados de bienes o trabajo, causados or la rigidez de precios y salarios. De otro lado se justifica el argumento keynesiano acerca de la intervención del gobierno, pues en algunos casos la economía por sí sola no puede superar una etapa recesiva.no-walrasiano, competencia imperfecta, ciclos económicos

Enhanced ICMR amplifier for high CMRR biopotential recordings

PostprintThis paper presents an integrated biopotential preamplifier architecture targeting applications that simultaneously require high common-mode rejection ratio (CMRR), low noise, high input common-mode range (ICMR), and current-efficiency (low Noise Efficiency Factor or NEF). A biopotential preamplifier, which performs well in line with the state-of-the-art of the field while providing enhanced ICMR and CMRR performance, was fabricated in a 0.5 μm CMOS process. Results from measurements show that the gain is 47 dB, the bandwidth ranges from 1 Hz to 7.7 kHz, the equivalent input noise is 1.8 μV rms , the CMRR is 100.5 dB, the ICMR is 1.7 V and the NEF is 3.2

EQUILIBRIO GENERAL NO COMPETITIVO CON FORMACIÓN ENDÓGENA DE PRECIOS

This article presents an equilibrium concept that, contrary to the traditional walrasian one, allows for the unbalance between supply and demand in different markets, making easier the analysis of those situations in which they differ persistently, as in the case of the labor market. Furthermore, the process of price setting becomes endogenous and it is shown that an equilibrium with endogenous price setting is a particular case of an equilibrium of fixed prices. Toward the end some examples are presented which help us to sustain these arguments.Equilibrio No-Walrasiano, Formación de Precios

Teaching for understanding approach in the english classes at próspero Pinzón and nuevo San Andrés de los Altos Schools in Bogotá

El presente trabajo de investigación con la acción concertada del Inglés con el enriquecimiento de la práctica educativa de los maestros a través de un proceso de reflexión en dos escuelas públicas en la ciudad de Bogotá con el objetivo de poner en práctica un enfoque institucional que permite el desarrollo de procesos socio-emocionales y cognitivas en los estudiantes.The purpose of this research is to enrich, whether it is possible, the English teaching processes implementing the principles of the Teaching for Understanding Approach at both schools. The TfU is a pedagogical approach that is characterized by the development of a class allowing the reflection, planning, design, presentation and evaluation of a topic to be carried out; based on the development of the understanding. The teachers from both schools took four workshops, which aimed to inform, reflect, enrich and transform their pedagogic practice through the application of the theoretical postulates of the TfU approach, to check some examples of didactic units explained by the researchers, and to design and present an individual microteaching sample based on the TfU principles. All these workshops were formulated with the intention of fostering the teachers’ performance in their personal growth and professional l achievement. The research has focused on the three tasks, which are the identification of the theoretical foundations of the Teaching for Understanding Approach, English Teaching, and Teachers´ Development, the analysis of the development of English classes on the light of the TfU principles and the definition, application and evaluation of four workshops in which teachers of both schools take part of activities about principles of the Teaching for Understanding Approach. The practical stage was divided in four workshops. These activities were carried out through the identification, the explanation, the teaching, analysis, and explanation of the seven principles of the TfU approach proposed by Tina Blythe. Also, several activities were developed with the teachers of both schools aiming to foster the critical thinking and the communicative skills of the students. The workshops were allocated in four stages. The first one was named sensitization and contextualization, the second stage was the identification and analysis of the 7 principles of the TfU, the third stage made reference to the design of a group lesson and finally the fourth stage was named as the design of a microteaching under the application of the seven principles of the TfU. The generated data have evidenced the importance of sharing knowledge among teachers in order to enrich the pedagogical practices to benefit the students´ learning processes. Also, it was concluded that principals and coordinators have to open more pedagogical spaces where teachers can develop useful activities. And finally it was evidenced that teachers can promote and encourage the creativeness, critical thinking, social relations and affective filter in their pupils, taking into consideration the students’ interests