Biodegradación de los componentes de mayor impacto en la gasolina

El benceno, tolueno, etilbenceno y la mezcla de xilenos (BTEX), junto con éter metil tert-butílico (EMTB) son compuestos orgánicos volátiles, estos junto con el etanol comúnmente son encontrados en sitios contaminados con gasolinas. En este estudio se evaluó la biodegradación de estos contaminantes mediante consorcios microbianos aclimatados a diferentes sustratos (diesel, gasolina, EMTB, pentano y pentano-EMTB) en sistemas aerobios de lote y de biopelícula de flujo continuo. A partir de éste ultimo sistema se lograron los máximos porcentajes de biodegradación que fueron casi de 100% para cada uno de los BTEX y etanol; y de 67.76% para el EMTB, a un tiempo de retención hidráulico de doce horas

Metallophilic fungi research: an alternative for its use in the bioremediation of hexavalent chromium

Contamination by hexavalent chromium has had a large impact on modern society and human health. This problem is a consequence of its great industrial applicability to several products and processes. Short-term exposure to hexavalent chromium can cause irritation, ulceration in skin and stomach and in addition to cancer, dermatitis, and damage to liver, renal circulation and nervous tissues, with even death being observed in response to long-term exposures. Many techniques have been used for the remediation of this pollutant, including physical and chemical approaches and, in more recent years, biological methods. Filamentous fungi isolated from contaminated sites exhibit a significant tolerance to heavy metal; hence, they are an important source of microbiota capable of eliminating hexavalent chromium from the environment. However, these microorganisms can do so in different ways, including biosorption, bioreduction, and bioaccumulation, among others. In this review, we explore several of the most documented mechanisms that have been described for fungi/hexavalent chromium interactions and their potential use in bioremediation

Modelo matemático de aceptación de la tecnología centrado en el uso de Google Classroom

La emergencia sanitaria causada el surgimiento del virus SARS-CoV-2 y sus variantes, tuvo implicaciones en todos los ámbitos de la actividad humana, y el educativo no fue la excepción. Por ello, se adoptó métodos de enseñanza aprendizaje basados en tecnologías de la información y la comunicación por la distancia social que se vive. El objetivo de la investigación es determinar los factores que influyeron en la utilización de Google Classroom, en estudiantes universitarios en dos instituciones de nivel superior correspondientes al Estado de Guanajuato - México, en base al modelo de aceptación de la tecnología, empleada para predecir su uso; se utilizó la modelación con ecuaciones estructurales con mínimos cuadrados parciales; se verifica la validez del modelo de medida y del modelo estructural, así como el ajuste global. En los resultados se encontró que la facilidad del uso influye de forma directa y positiva en la utilidad que los estudiantes perciben (R2=0.642), que la intención de uso de Google Clasroom está determinada de forma directa y positiva por la facilidad de uso y la utilidad percibida (R2=0.590), que la intención de emplear Google Classroom influye de forma directa y positiva el uso de dicho recurso (R2=0.219)

DISEÑO DE UN INSTRUMENTO PARA MEDIR LA COMPETENCIA PERSONAL Y ESTABLECIMIENTO DE METAS, CULTURA ORGANIZACIONAL, CLIMA ORGANIZACIONAL DE LA EMPRESA SAN TELMO SA DE CV

ResumenLa presente investigación consistió en el diseño y validación de un instrumento de medición basado en estrategias de endomarketing para la empresa San Telmo SA de CV, que cabe resaltar que tiene un alto índice de rotación de personal (200%). El employer brading consiste en la combinación de recursos humanos y marketing, cuyo objetivo es proyectar una buena imagen de la empresa al trabajador y que éste a su vez la refleje en la sociedad. Se adaptó el modelo de endomarketing de Christian Gronroos (2002) y se elaboró un instrumento de medición del establecimiento de metas, clima y la cultura organizacional basado en Hellriegel Slocum (2009). Los resultados indican un alto índice de fiabilidad (0.942) que fue medido a través del estadístico Alfa de Cronbach vía el software SPSS versión 2017.Palabras clave: Clima organizacional, Cultura organizacional, Endomarketing.DESIGN OF AN INSTRUMENT TO MEASURE PERSONAL COMPETENCE AND GOAL SETTING, ORGANIZATIONAL CULTURE, ORGANIZATIONAL CLIMATE OF THE COMPANY SAN TELMO SA DE CVAbstractThe present investigation consisted of the design and validation of a measurement instrument based on endomarketing strategies for the company San Telmo S.A. of C.V., which should be noted that has a high turnover rate of staff (200%). The employer brading consists of the combination of human resources and marketing, whose objective is to project a good image of the company to the worker and which in turn reflects it in society. The endomarketing model of Christian Gronroos (2002) was adapted and an instrument to measure goal setting, climate and organizational culture was elaborated based on Hellriegel Slocum (2009). The results indicate a high reliability index (0.942) that was measured through the statistic Cronbach's Alpha via software SPSS version 2017.Keywords: Endomarketing, Organizational climate, Organizational culture

ANÁLISIS ECONOMÉTRICO DE LAS VENTAS DE PULPA DE MANGO DE FROZEN PULPS DE MÉXICO SA DE CV

ResumenEn este trabajo se realizó un análisis económico de las ventas de pulpa de mango de Frozen Pulps de México SA de CV, con el propósito de establecer estadísticamente los factores que las determinan. Para lograr lo anterior se formuló un modelo econométrico sustentado en la teoría de la oferta, se conformaron series de tiempo para las variables involucradas con información anual de 2004 a 2014 y, la ecuación de regresión fue estimada vía mínimos cuadrados ordinarios (MCO). Los resultados indican que el precio propio de la producción de mango, el precio de exportación y el tipo de cambio son factores que inciden positiva e intensamente en las ventas de exportación de pulpa de mango de la empresa. El salario mínimo general es el factor que registró el valor de elasticidad económica más alto (en términos absolutos) sobre las ventas (-2.65), seguido por el tipo de cambio (1.96).Palabras clave: Exportación, modelo econométrico, pulpa de mango. AbstractThis paper presents an economic analysis of sales of Frozen Pulps de Mexico SA de CV, in order to establish statistically determining factors. To achieve this an econometric model based on the theory of supply was made, time series were formed for the variables involved with annual data from 2004 to 2014 and the regression equation was estimated with ordinary least squares minimun (OLS). The results indicate that the proper price of mango production, export price and exchange rate are factors that impact positively and intensely in export sales of company. The general minimum wage is the factor which recorded the highest economic value of elasticity (in absolute terms) on sales (-2.65), followed by the exchange rate (1.96).Keywords: Export, econometric model, mango pulp

Metal-Induced Production of a Novel Bioadsorbent Exopolysaccharide in a Native Rhodotorula mucilaginosa from the Mexican Northeastern Region

There is a current need to develop low-cost strategies to degrade and eliminate industrially used colorants discharged into the environment. Colorants discharged into natural water streams pose various threats, including: toxicity, degradation of aesthetics and inhibiting sunlight penetration into aquatic ecosystems. Dyes and colorants usually have complex aromatic molecular structures, which make them very stable and difficult to degrade and eliminate by conventional water treatment systems. The results in this work demonstrated that heavy metal-resistant Rhodotorula mucilaginosa strain UANL-001L isolated from the northeast region of Mexico produce an exopolysaccharide (EPS), during growth, which has colorant adsorption potential. The EPS produced was purified by precipitation and dialysis and was then physically and chemically characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and chemical elemental analysis. Here, the ability of the purified EPS produced to adsorb methylene blue (MB), which served as a model colorant, is studied. MB adsorption by the EPS is found to follow Langmuir Adsorption Isotherm kinetics at 25°C. Further, by calculating the Langmuir constant the adsorption capabilities of the EPS produced by the Rhodotorula mucilaginosa strain UANL-001L is compared to that of other adsorbents, both, microbially produced and from agroindustrial waste. The total adsorption capacity of the EPS, from the Rhodotorula mucilaginosa strain UANL-001L, was found to be two-fold greater than the best bioadsorbents reported in the literature. Finally, apart from determining which heavy metals stimulated EPS production in the strain, the optimal conditions of pH, heavy metal concentration, and rate of agitation of the growing culture for EPS production, was determined. The EPS reported here has the potential of aiding in the efficient removal of colorants both in water treatment plants and in situ in natural water streams

La memoria de los libros. Estudios sobre la historia del escrito y de la lectura en Europa y América. Vol. I

Numerosos artículos sobre aspectos variados de historia del libro y de la lectura, bibliotecas, manuscritos, iluminación e ilustración, etc

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality