Lixiviacion de mineral aurifero de vetas santander, con sales oxidantes en medio acido

El trabajo de lixiviación para la extracción de oro se llevó a cabo con mineral aurífero concentrado proveniente de la Empresa Minera Rey de Oro, el cual se caracterizó para obtener la información mineralógica, geoquímica y fisicoquímica necesaria para el desarrollo del proceso. El medio lixiviante utilizado se forma en la pulpa con el ácido sulfúrico concentrado adicionando sales oxidantes como el cloruro de sodio y el nitrato de sodio. La adición de sales a la pulpa ácida tiene por finalidad producir cloro y agua regia in situ, lixiviante enérgico para recuperar elementos nobles de concentrados o mineral auríferos. Los resultados obtenidos en la investigación muestran que es posible lixiviar oro de mineral aurífero por el proceso de lixiviación con sales oxidantes en medio ácido. Sin embargo los porcentajes de disolución alcanzados no superan el 20% esto es debido a la formación de jarosita fase mineralógica que actúa de forma negativa en el proceso de lixiviación

Lixiviacion de mineral aurifero de vetas santander, con sales oxidantes en medio acido

El trabajo de lixiviación para la extracción de oro se llevó a cabo con mineral aurífero concentrado proveniente de la Empresa Minera Rey de Oro, el cual se caracterizó para obtener la información mineralógica, geoquímica y fisicoquímica necesaria para el desarrollo del proceso. El medio lixiviante utilizado se forma en la pulpa con el ácido sulfúrico concentrado adicionando sales oxidantes como el cloruro de sodio y el nitrato de sodio. La adición de sales a la pulpa ácida tiene por finalidad producir cloro y agua regia in situ, lixiviante enérgico para recuperar elementos nobles de concentrados o mineral auríferos. Los resultados obtenidos en la investigación muestran que es posible lixiviar oro de mineral aurífero por el proceso de lixiviación con sales oxidantes en medio ácido. Sin embargo los porcentajes de disolución alcanzados no superan el 20% esto es debido a la formación de jarosita fase mineralógica que actúa de forma negativa en el proceso de lixiviación

Use Of Sensors In Chemistry Class And The Development Of Scientific competence

RESUMEN Los resultados obtenidos por los estudiantes de educación media, en los años 2008 y 2009 en Colombia, en el examen de estado aplicado por el ICFES y en las pruebas internacionales como PISA, se concluye que aún hay trabajo por realizar en la escuela con el fin de fomentar el desarrollo de las competencias científicas. Los colegios oficiales de Bogotá, están siendo dotados de herramientas tecnológicas para ser utilizadas en el aula. El uso de estas herramientas, necesita ser estudiado para identificar sus fortalezas y debilidades en el proceso de enseñanza de los modelos químicos, razón por la cual la presente investigación indaga sobre la influencia de la aplicación de una estrategia basada en el aprendizaje por investigación apoyada en el uso de sensores en el desarrollo de competencias científicas en estudiantes de educación media. El estudio se desarrolla en el marco de la investigación–acción, introduciendo dentro de las actividades desarrolladas en clase de química los sensores y sistemas de adquisición automática de datos, que forman parte de las nuevas tecnologías de la información y la comunicación que se han adaptado a la escuela, con el objetivo de estudiar el efecto que producen en las estructuras presentes en el estudiante frente a las competencias científicas construidas por él en su entorno escolar. ABSTRACT The results obtained by students of middle education in the years 2008 and2009 in Colombia, in the state exam applied by ICFES and international testsas PISA, it is concluded that there is still work to carry out in the school with thepurpose of fomenting the development of the scientific competences. Thepublic schools of Bogotá, are being equipped with technological tools for usein the classroom. Use of these tools need to be studied to identify theirstrengths and weaknesses in the teaching of chemistry models, explainingwhy this research investigates the impact of implementing a learning strategybased on research supported by the use of sensors in the development ofscientific expertise in middle school students. The study is developed in theframework of investigation- action, introducing into the class of the chemicalsensors and systems for automatic data acquisition, as part of the NewInformation and Communication Technologies that have adapted to theschool, with the objective of studying their effect produced on the structurespresents in upon scientific competences built by him in his schoolenvironment

Gestión pedagógica: propuesta para favorecer el aprendizaje en ética en estudiantes de segundo grado de la institución educativa distrital Tomás Cipriano de Mosquera

La sociedad está en crisis, vivimos en una realidad que promueve el consumo indiscriminado, el individualismo, la agresividad creciente, a los que nuestra niñez, para este caso la primera infancia, no se escapa, sino que por el contrario, se manifiesta a diario en la escuela. Es necesario que esta promueva la participación de cada uno de los miembros de manera organizada a través de mecanismos legitimados institucionalmente, pensada como actividades enmarcadas desde la gestión pedagógica, para lograr una secuencia educativa que tenga como objetivo la elaboración, evaluación, reconstrucción de pautas y modos de socialización grupales e institucionales, en el marco de los propios procesos de enseñanza y aprendizaje, resignificando el proceso educativo en la escuela.Es aquí donde el papel de la concepción de educar en ética, debe estar estrecha y filialmente ligado con un proceso actitudinal progresivo. Pensarse desde una serie de procesos apoyados en la pedagogía, cuyo fin último nos podrá revelar la transformación en el educando con relación a la consolidación de sus principios, el cuestionamiento de sus actitudes y aptitudes, lo cual considera los campos ético, cívico, creativo y crítico de cada uno de los participantes, generando así conciencia a partir de situaciones provocadas en ambientes y habilidades personales, garantizando destrezas y acciones sociales. Este proyecto surge entonces, por la necesidad de crear ambientes educativos enmarcados dentro del aprendizaje de la ética y la gestión pedagógica, cuyo fin sea el de convivir y aprender, que se desarrolle en los y las estudiantes un compromiso social, promoviendo actitudes positivas con una puesta en escena coherente entre sus pensamientos y sus comportamientos, de una forma continua e innovadora que impacten favorablemente a la sociedad

Dental Amalgam Restorations and Children’s Neuropsychological Function: The New England Children’s Amalgam Trial

BACKGROUND: A concern persists that children’s exposure to mercury vapor from dental amalgams produces neurotoxicity. OBJECTIVE: Our goal was to compare the neuropsychological function of children, without prior exposure to dental amalgam, whose caries were repaired using either dental amalgam or mercury-free composite materials. METHODS: We conducted a randomized controlled trial involving 534 6- to 10-year-old urban and rural children who were assessed yearly for 5 years using a battery of tests of intelligence, achievement, language, memory, learning, visual–spatial skills, verbal fluency, fine motor function, problem solving, attention, and executive function. RESULTS: Although the mean urinary mercury concentration was greater among children in the amalgam group than the composite group (0.9 vs. 0.6 μg/g creatinine), few significant differences were found between the test scores of children in the two groups. The differences found were inconsistent in direction. Analyses using two cumulative exposure indices—surface years of amalgam and urinary mercury concentration—produced similar results. CONCLUSIONS: Exposure to elemental mercury in amalgam at the levels experienced by the children who participated in the trial did not result in significant effects on neuropsychological function within the 5-year follow-up period

Timing of Fluoride Intake and Dental Fluorosis On Late-Erupting Permanent Teeth

Objective: Very few studies have examined the relationship between timing of fluoride intake and development of dental fluorosis on late-erupting permanent teeth using period-specific fluoride intake information. This study examined this relationship using longitudinal fluoride intake information from the Iowa Fluoride Study. Methods: Participants’ fluoride exposure and intake (birth to 10 years of age) from water, beverages, selected food products, dietary fluoride supplements, and fluoride toothpaste was collected using questionnaires sent to parents at 3- and 4- month intervals from birth to 48 months of age and every 6 months thereafter. Three trained and calibrated examiners used the Fluorosis Risk Index (FRI) categories to assess 16 late-erupting teeth among 465 study participants. A tooth was defined as having definitive fluorosis if any of the zones on that tooth had an FRI score of 2 or 3. Participants with questionable fluorosis were excluded from analyses. Descriptive and logistic regression analyses were performed to assess the importance of fluoride intake during different time periods. Results: Most dental fluorosis in the study population was mild, with only four subjects (1%) having severe fluorosis (FRI Score 3). The overall prevalence of dental fluorosis was 27.8%. Logistic regression analyses showed that fluoride intake from each of the individual years from age 2 to 8 plays an important role in determining the risk of dental fluorosis for most late-erupting permanent teeth. The strongest association for fluorosis on the late-erupting permanent teeth was with fluoride intake during the sixth year of life. Conclusion: Late-erupting teeth may be susceptible to fluorosis for an extended period from about age 2 to 8. Although not as visually prominent as the maxillary central incisors, some of the late-erupting teeth are esthetically important and this should be taken into consideration when making recommendations about dosing of fluoride intake

PLANEACIÓN DIDÁCTICA GENERAL DE LA ASIGNATURA: HERENCIA Y EVOLUCIÓN

GUÍA DIDÁCTICA / PLANEACIÓN DIDÁCTICA (NMS

Simulation of a solar-assisted air-conditioning system applied to a remote school

Producción CientíficaIn this work, we present an absorption cooling system with 35 kW capacity driven by solar thermal energy, installed in the school of Puertecitos, Mexico, an off-grid community with a high level of social marginalization. The cooling system provides thermal comfort to the school’s classrooms through four 8.75-kW cooling coils, while a 110-m2 field of evacuated tube solar collectors delivers the thermal energy needed to activate the cooling machine. The characteristics of the equipment installed in the school were used for simulation and operative analysis of the system under the influence of typical factors of an isolated coastal community, such as the influence of climate, thermal load, and water consumption in the cooling tower, among others. The aim of this simulation study was to determine the best operating conditions prior to system start-up, to establish the requirements for external heating and cooling services, and to quantify the freshwater requirements for the proper functioning of the system. The results show that, with the simulated strategies implemented, with a maximum load operation, the system can maintain thermal comfort in the classrooms for five days of classes. This is feasible as long as weekends are dedicated to raising the water temperature in the thermal storage tank. As the total capacity of the system is distributed in the four cooling coils, it is possible to control the cooling demand in order to extend the operation periods. Utilizing 75% or less of the cooling capacity, the system can operate continuously, taking advantage of stored energy. The cooling tower requires about 750 kg of water per day, which becomes critical given the scarcity of this resource in the community.CONACYT-SENER-SUSTENTABILIDAD ENERGÉTICA (project P09)Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (project 518RT0558

Automatic aggregation of subtask accesses for nested OpenMP-style tasks

Task-based programming is a high performance and productive model to express parallelism. Tasks encapsulate work to be executed across multiple cores or offloaded to GPUs, FPGAs, other accelerators or other nodes. In order to maintain parallelism and afford maximum freedom to the scheduler, the task dependency graph should be created in parallel and well in advance of task execution. A key limitation with OpenMP and OmpSs-2 tasking is that a task cannot be created until all its accesses and its descendents' accesses are known. Current approaches to work around this limitation either stop task creation and execution using a taskwait or they substitute “fake” accesses known as sentinels. This paper proposes the auto clause, which indicates that the task may create subtasks that access unspecified memory regions or it may allocate and return memory at addresses that are of course not yet known. Unlike approaches using taskwaits, there is no interruption to the concurrent creation and execution of tasks, maintaining parallelism and the scheduler's ability to optimize load balance and data locality. Unlike existing approaches using sentinels, all tasks can be given a precise specification of their own data accesses, so that a single mechanism is used to control task ordering, program data transfers on distributed memory and optimize data locality, e.g. on NUMA systems. The auto clause also provides an incremental path to develop programs with nested tasks, by removing the need for every parent task to have a complete specification of the accesses of its descendent tasks. This is redundant information that can be time consuming and error-prone to describe. We present a straightforward runtime implementation that achieves a 1.4 times speedup for n-body with OmpSs-2@Cluster task offloading to 32 nodes and <4% slowdown for three benchmarks with task offloading to 8 nodes. All code is open source.This research has received funding from the European Unions Horizon 2020/EuroHPC research and innovation programme under grant agreement No 955606 (DEEP- SEA) and 754337 (EuroEXA). It is supported by the Spanish State Research Agency - Ministry of Science and Innovation (contract PID2019-107255GB- C21/MCIN/AEI/10.13039/501100011033 and Ramon y Cajal fellowship RYC2018-025628-I/MCIN/AEI/ 10.13039/501100011033 and by “ESF Investing in your future”), as well as by the Generalitat de Catalunya (2017-SGR-1414).Peer ReviewedPostprint (author's final draft