Mecanismos de resistencia a arsénico por la corinebacteria Corynebacterium glutamicum

El arsénico (As) es uno de los metales que forma parte de la composición de muchos minerales. Las corinebacterias han sido objeto de especial análisis en procesos biotecnológicos, concretamente la Corynebacterium glutamicum ATCC 13032 presenta una inusitada resistencia a formas inorgánicas de arsénic

Corynebacterium glutamicum as a model bacterium for the bioremediation of arsenic

Arsenic is an extremely toxic metalloid that, when present in high concentrations, severely threatens the biota and human health. Arsenic contamination of soil, water, and air is a global growing environmental problem due to leaching from geological formations, the burning of fossil fuels, wastes generated by the gold mining industry present in uncontrolled landfills, and improper agriculture or medical uses. Unlike organic contaminants, which are degraded into harmless chemical species, metals and metalloids cannot be destroyed, but they can be immobilized or transformed into less toxic forms. The ubiquity of arsenic in the environment has led to the evolution in microbes of arsenic defense mechanisms. The most common of these mechanisms is based on the presence of the arsenic resistance operon (ars), which codes for: (i) a regulatory protein, ArsR; (ii) an arsenite permease, ArsB; and (iii) an enzyme involved in arsenate reduction, ArsC. Corynebacterium glutamicum, which is used for the industrial production of amino acids and nucleotides, is one of the most arsenic-resistant microorganisms described to date (up to 12 mM arsenite and >400 mM arseniate). Analysis of the C. glutamicum genome revealed the presence of two complete ars operons (ars1 and ars2) comprising the typical three-gene structure arsRBC, with an extra arsC1´ located downstream from arsC1 (ars1 operon), and two orphan genes (arsB3 and arsC4). The involvement of both ars operons in arsenic resistance in C. glutamicum was confirmed by disruption and amplification of those genes. The strains obtained were resistant to up to 60 mM arsenite, one of the highest levels of bacterial resistance to arsenite so far described. Using tools for the genetic manipulation of C. glutamicum that were developed in our laboratory, we are attempting to obtain C. glutamicum mutant strains able to remove arsenic from contaminated water. [Int Microbiol 2006; 9(3):207-215

La filtración gruesa, aplicada al tratamiento de aguas superficiales

El presente trabajo busca proporcionar criterios básicos de diseño para la implementación de filtros gruesos FG, siendo de vital importancia en el medio rural donde no es apropiado el uso de tecnología convencional para potabilización debido a la ausencia de mano de obra especializada, así como en sistemas de tratamiento que emplean filtros lentos, sin un pretratamiento con FG. La tecnología debe ser adaptada según las características propias de cada fuente de abastecimiento considerando las condiciones locales La ausencia de plantas de tratamiento, con sistemas de pretratamiento correctamente implementados, provoca su deterioro y posterior colapso. Considerando la problemática existente se ha investigado los FG, como mecanismo para el mejoramiento de la cobertura cualitativa, al ser unidades de bajo costo de construcción y operación que no utilizan productos químicos en su operación.The present work seeks to provide basic design criteria for the implementation of carouse filters CF, these must be adapted according to the characteristics of each source of supply, being of vital importance in the rural environment where it is not appropriate to use conventional technology for potabilization based on coagulation, flocculation, sedimentation and filtration, due to the absence of specialized labor, as well as in treatment systems that use slow filters, without a pretreatment with CF, making it impossible to function properly and in cases where have been applied, are used in a standardized way without regard to local conditions. The absence of treatment plants, with correctly implemented pretreatment systems, causes their deterioration and subsequent collapse. Considering the existing problem, the CF have been investigated as a mechanism to improve the qualitative coverage, they are low cost units of construction and operation that do not use chemicals in their operation.Ingeniero CivilCuenc

Diseño y simulación de una máquina para aplicar pintura epóxica al interior de tuberías de acero de 24 a 30 pulgadas para uso industrial

The application of liquid coatings on metal surfaces plays a fundamental role on the coated material, the application of paint to surfaces is to prevent corroding, as it is known the metal is made of a mineral called ferric oxide which is applied high energy to extracting the iron and it tends to return to its original state through oxidation, a problem that represents high investments in maintenance. The methods of applying paint in the industry is through manual processes, methods that do not save productive times and decrease the production and compromise the safety of an operator, the lack of research to automate processes causes setbacks not to be parallel with the technological advance. The present research is focused on taking the first step to solve aspects that do not compromise the safety of an operator only for the economic saving, this investigation is oriented to change the techniques of application of painting, in automating processes by means of machinery that performs activities of apply paint and discard techniques manually. The present research is focused on taking the first step to solve aspects that do not compromise the safety of an operator only for the economic saving, this investigation is oriented to change the techniques of application of painting, in automating processes by means of machinery that performs activities of apply paint and discard techniques manually.La aplicación de recubrimientos líquidos sobre superficies metálicas desempeña un papel fundamental sobre el material recubierto porque evita la corrosión. El metal es realizado de un mineral llamado oxido férrico al que se le aplica alta energía para extraer el hierro y el mismo tiende a volver a su estado original mediante la oxidación, problema que representa altas inversiones en mantenimiento. Los métodos de aplicación de pintura en la industria son mediante procesos manuales, métodos que nos ahorran tiempos productivos, disminuyen la producción y comprometen la seguridad de un operario, la falta de investigación para automatizar procesos causa retrocesos al no ir paralela con el avance tecnológico. La presente investigación está enfocada a dar el primer paso para solucionar aspectos que no comprometan la seguridad de un operario, tan solo por el ahorro económico. Esta investigación se orienta a cambiar las técnicas de aplicación de pintura, en automatizar procesos mediante maquinaria que ejecute actividades de aplicación de pintura y descartar técnicas de forma manual. El diseño y simulación del equipo se realizó mediante software avanzado, programas que permitieron diseñar, simular y mostrar el desempeño de la máquina diseñada. El uso de materiales estandarizados permitirá la facilidad en su construcción. Este aporte al campo de la pintura brindará beneficios a empresas que hagan uso de este equipo

La lúdica y la lectoescritura en el tercer grado de educación básica

The objective of the study was to determine the contribution of playful learning in third grade reading and writing. The research was carried out with a quantitative, descriptive approach, with a non-experimental design; the methods: documentary, hermeneutic, analytical and statistical; the techniques: observation and survey; the instruments: questionnaire and Dr. Ricardo Olea's reading and writing test, which prevailed due to its pedagogical nature. The sampling was non-probabilistic and included 3 teachers and 22 students. Regarding to the obtained results, most of the scales are deficient in different intensity, the highest percentage was deficient reading and writing in intense grade. Therefore, it was concluded that literacy is an essential process, because through its learning, the child defines language as the best option to communicate, express ideas and feelings. However, the students showed several deficiencies, and it demostrated that most teachers are not making use of playful strategies in learning.El objetivo del estudio fue determinar el aporte de la lúdica en la lectoescritura del tercer grado. La investigación se realizó con un enfoque cuantitativo, de tipo descriptivo, con diseño no experimental; los métodos: documental, hermenéutico, analítico y estadístico; las técnicas: observación y encuesta; los instrumentos: cuestionario y prueba de lectura y escritura del Dr. Ricardo Olea la misma que prevaleció por su carácter pedagógico. El muestreo fue no probabilístico, incluyó 3 docentes y 22 estudiantes. Respecto a los resultados obtenidos, la mayoría de escalas son deficientes en distintos grados, el porcentaje más alto fue lectoescritura deficiente en grado intenso. Por ende, se concluyó que la lectoescritura es un proceso esencial, porque mediante su aprendizaje el niño define al lenguaje como la mejor opción para comunicarse, expresar ideas y sentimientos. Sin embargo, los estudiantes presentaron varias deficiencias, y se evidenció que la mayoría de docentes no está haciendo uso de las estrategias lúdicas en el aprendizaje

Characterization of the promoter region of ftsZ from Corynebacterium glutamicum and controlled overexpression of FtsZ

Of the five promoters detected for the ftsZ gene in Corynebacterium glutamicum, three were located within the coding region of the upstream ftsQ gene and two within the intergenic ftsQ-ftsZ region. The most distant ftsZ promoter showed activity in Escherichia coli and controlled high-level transcriptional expression of ftsZ in C. glutamicum. Quantitative Western blotting showed that all five promoters were active during the exponential growth phase and down-regulated during stationary phase. This tightly controlled expression of ftsZ in C. glutamicum indicated that small changes in the amount of FtsZ protein strongly affect bacterial cell viability. The controlled overexpression of ftsZ in C. glutamicum, using the promoter of the gntK gene (PgntK), resulted in approximately 5-fold overproduction of FtsZ, an increase in cell diameter, and a highly variable localization of the protein as spirals or tangles throughout the cell. These results suggest that the intracellular concentration of FtsZ is critical for productive septum formation in C. glutamicum. Our observations provide insight into the mechanisms used by the coryneform group, which lacks actin homologs and many regulators of cell division, to control cell morphology. [Int Microbiol 2007; 10(4): 271-282

Planeamiento estratégico del sector escuelas de negocios en Colombia

La presente tesis tiene como objetivo la elaboración de un planeamiento estratégico del sector de Escuelas de Negocios en Colombia. El análisis cubre un marco muy completo que incluye la evaluación externa e interna del sector, sus intereses y objetivos a largo y corto plazo así como un análisis competitivo entre otros. El estudio revela desde el principio una enorme oportunidad de crecimiento y desarrollo para el sector de Escuelas de Negocios en Colombia dado principalmente por su bajo nivel de desarrollo actual y su alta demanda actual y potencial. Sumado a esto también se identifica una clara concentración en la ciudad capital abriendo un espectro de necesidades insatisfechas a nivel nacional y también unas condiciones políticas y económicas favorables para la inversión en Colombia. El presente planeamiento estratégico se ha elaborado usando como marco conceptual el Proceso Estratégico: Una Visión General de D’Alessio (2008) así como los materiales y enseñanzas de la asignatura Administración Estratégica y Liderazgo. Se usaron diferentes fuentes de información para documentar el análisis, las principales fuentes fueron las mismas escuelas de negocios, revistas especializadas y diarios. Como ya lo hemos mencionado, el resultado de este planeamiento estratégico nos ilustra claramente un sector con gran oportunidad de crecimiento y expansión geográfica, donde la tendencia de demanda es creciente y lo seguirá siendo, mientras que la oferta nacional aún es insuficiente. Escuelas de Negocios extranjeras han venido detectando esta evidente oportunidad de negocio y ya han ido buscando formas de tomar parte del mercado con éxito. El presente planeamiento estratégico plantea adicionalmente los objetivos de largo y corto plazo y recomienda un camino para su desarrollo destacado en la región.This thesis has as its main objective the development of a strategic plan for the Business School sector in Colombia. The analysis is very wide and includes external and internal evaluation of the sector, its interests and long and short term objectives as well as a competitive analysis, among others. The study shows from the beginning for the Business Schools sector in Colombia, a huge opportunity to grow and develop due mainly to the current low development of the sector and the high and growing demand. Also we detected a high concentration of availability in the country’s capital city opening a broad opportunity to satisfy consumer needs nationwide and favorable economic and political country conditions. As we mentioned, the result of this strategic plan clearly highlights a sector with a great growth and geographic expansion potential. Demand is growing and has a growing tendency and local offer is still not enough. Foreign business schools have started to see this opportunity and have started to successfully start to gain part of the available market. This strategic plan also establishes long and short term objectives as well as a recommended pathway for an outstanding development within the region. Currently in Colombia only one Business School has three international certifications so the pathway for local evolution has to be speeded up in order to become a regional model for the sector.Tesi

Los indicios auríferos sobre la Fm Vegadeo en el corredor Navelgas-Trevías (Zona Asturoccidental-Leonesa)

In this paper, some results of practical interest regarding the gold mineralisation occurring in the northern area of the Navelgas gold belt (West Asturian-Leonese Zone) are presented. The mineral paragenesis of the Navelgas hydrothermal-type mineralization has been completed with the presence of arsenopyrite, lollingite, native Bi, bismuthinite, gersdorfite, violarite, monazite and parisite. Native gold, although scarce, is mainly associated with pyrite and asenopyrite. Pyrite, predominant sulphide, contains 625 mg-kg-1 of invisible refractory gold. Micro-analysis of trace elements in alluvial gold particles indicates the presence of several unknown primary gold showings, likely associated with quartz veins, in the upper basin of the Navelgas river. In the San Feliz area, about 12 km NE of Navelgas, refractory gold (727 mg-kg-1) has been identified in the goethite (pseudomorph of pyrite) within the eluvium overlying the Vegadeo Fm, suggesting the possible existence of deep mineralized areas.En este trabajo se presentan algunos resultados de interés práctico sobre las mineralizaciones de oro que aparecen en el sector norte del cinturón aurífero de Navelgas (Zona Asturoccidental-Leonesa). El indicio de Navelgas, el más importante del área de estudio, presenta una mineralización hidrotermal cuya paragénesis se ha completado con la presencia de arsenopirita, lollingita, Bi nativo, bismutinita, gersdorfita, violarita, monacita y parisita. El oro nativo, escaso, se asocia a pirita y asenopirita. La primera, mayoritaria, contiene 625 mg·kg-1 de oro refractario invisible. El microanálisis de elementos traza en oro aluvionar indica que en la cuenca alta del río Navelgas existen varios indicios, no conocidos, de oro primario, probablemente asociados a filones de cuarzo. En el área de San Feliz, unos 12 km al NE de Navelgas, se ha identificado la presencia de oro refractario (727 mg·kg-1) en la goethita (pseudomorfa de pirita) de los eluviones que se desarrollan sobre la Fm Vegadeo, lo que parece indicar la posible existencia de zonas profundas mineralizadas. En el área de San Feliz, unos 12 km al NE de Navelgas, se ha identificado la presencia de oro refractario (727 mg·kg-1) en la goethita (pseudomorfa de pirita) de los eluviones que se desarrollan sobre la Fm Vegadeo, lo que parece indicar la posible existencia de zonas profundas mineralizadas

Análisis Financiero para la Implementación de un Bus Eléctrico Urbano en la Ciudad de Cuenca

The present paper carried out a financial analysis that allows establishing the economic feasibility of implementing electric buses for urban service in the city of Cuenca, which circulate through urban routes that connect the main university campuses of the city, which is located at 2 560 meters above sea level and has an urban population of 329 928 inhabitants; for this purpose, five urban routes were established that allow the connection between the universities, proposing routes with lengths of 14 to 34 km, with a duration of 30 minutes to one hour and fifteen minutes, considering the mobilization of 40 000 students. The costs of analysis include income, which implies the value of the ticket and mobile advertising, on the other hand, there are the expenses, such as the acquisition of the unit, maintenance and spare parts, financing and operating expenses; once the values are determined, net present value (NPV) and internal rate of return (IRR) conditions are applied. As a result, lower and negative values are obtained, resulting in an unprofitable project, and this is due to the $0.31 ticket value; as a conclusion and in order for the project to be profitable, a 61 to 83$ 0.31. Como conclusión, y para que el proyecto sea rentable, se considera una elevación del pasaje en un 61 al 83 %