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Methotrexate (MTX) is a folic acid analog and has been used to treat a wide variety of malignant and non-malignant diseases. The wide use of these substances has led to the continuous discharge of the parent compound and its metabolites in wastewater. In conventional wastewater treatment plants, the removal or degradation of drugs is not complete. In order to study the MTX degradation by photolysis and photocatalysis processes, two reactors were used with TiO2 as a catalyst and UV-C lamps as a radiation source. H2O2 addition was also studied (absence and 3 mM/L), and different initial pHs (3.5, 7, and 9.5) were tested to define the best degradation parameters. Results were analyzed by means of ANOVA and the Tukey test. Results show that photolysis in acidic conditions with 3 mM of H2O2 added is the best condition for MTX degradation in these reactors, with a kinetic constant of 0.028 min-1. According to the ANOVA test, all considered factors (process, pH, H2O2 addition, and experimentation time) caused statistically significant differences in the MTX degradation results.

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Phenol is used in the manufacturing process of phenolic resins from which residues remain that must be sent for confinement. For that reason, in this study, the wastewater of a resin factory was analyzed to isolate the bacteria present, identify them by molecular methods and finally evaluate their impact on bioremediation treatment. A total of 15 bacteria were isolated, of these, eight belong to the genus Bacillus spp. All bacteria were individually multiplied and inoculated in clusters in 15 L reactors which were carefully monitored for pH, electrical conductivity, chemical oxygen demand and temperature. The acquired data were analyzed using ANOVA with repeated measurements. The first test revealed that native bacterial communities reduce the phenol content by up to 20% and COD by 49%, which is significant with respect to the reactor not being inoculated with bacteria. Furthermore, when a mathematical model was applied to the reactors, it was shown that the bacteria require an adaptation time of approximately 100 h. A second test where the inoculation was interspersed with the addition of lime as a flocculant showed that, even though the reduction in phenol and COD was lower than in the previous test, the difference between treatments and control is statistically significant (α ≤ 0.05).

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ß-Glucosidase is part of the cellulases and is responsible for degrading cellobiose into glucose, a compound that can be used to produce biofuels. However, the use of the free enzyme makes the process more expensive. Enzyme immobilization improves catalytic characteristics and supports, such as zeolites, which have physical-chemical characteristics and ion exchange capacity that have a promising application in the biotechnological industry. This research aimed to immobilize by adsorption a recombinant ß-glucosidase from Trichoderma reesei, obtained in Escherichia coli BL21 (DE3), in a commercial zeolite. A Box Behnken statistical design was applied to find the optimal immobilization parameters, the stability against pH and temperature was determined, and the immobilized enzyme was characterized by SEM. The highest enzymatic activity was determined with 100 mg of zeolite at 35 °C and 175 min. Compared to the free enzyme, the immobilized recombinant ß-glucosidase presented greater activity from pH 2 to 4 and greater thermostability. The kinetic parameters were calculated, and a lower KM value was obtained for the immobilized enzyme compared to the free enzyme. The obtained immobilization parameters by a simple adsorption method and the significant operational stability indicate promising applications in different fields.

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Los trabajadores de hatos lecheros están en constante riesgo de contraer enfermedades zoonóticas como la brucelosis, tuberculosis, leptospirosis y carbunco bacteridiano, por la exposición a agentes biológicos y el contacto directo con animales durante el desarrollo de sus labores. Se describe el nivel de conocimientos, actitudes, prácticas, percepción de riesgo y las características sociodemográficas de los trabajadores de hatos lecheros de la colonia 07 Montes del distrito de Curuguaty, frente a las zoonosis, en el último trimestre del 2019. Fue un estudio cuantitativo, observacional, descriptivo, de corte transversal en el cual se utilizó un cuestionario con 33 preguntas aplicado a 121 trabajadores, con el que se recogieron variables demográficas, conocimientos, actitudes, prácticas y percepción de riesgo. Los datos se analizaron a través del programa estadístico SPSS. Para el análisis univariado, se empleó la estadística descriptiva para representar los datos expresados en frecuencias, porcentajes y tablas. El 52,9 % de los trabajadores tenía conocimiento sobre la brucelosis, tuberculosis y leptospirosis, el 74,4 % tenía actitudes positivas, el 66,9% implementaba prácticas positivas y el 52,9% percibía el riesgo. Menos del 75% de los trabajadores encuestados tenían conocimientos, actitudes, prácticas y percepciones de riesgo óptimos, lo que resulta preocupante considerando la exposición constante de los mismos a las enfermedades zoonóticas, es por ello que se deberían implementar estrategias educativas de carácter multisectorial concernientes a estas patologías y sus medidas preventivas a modo de mejorar esta situación

Dairy herd workers are at constant risk of contracting zoonotic diseases such as brucellosis, tuberculosis, leptospirosis and anthrax, due to exposure to biological agents and direct contact with animals during the performance of their work. The level of knowledge, attitudes, practices, risk perception and sociodemographic characteristics of dairy herd workers in the 07 Montes colony of the Curuguaty district against zoonosis was described in the last trimester of 2019. A quantitative, observational study, descriptive, cross-sectional, in which a questionnaire with 33 questions applied to 121 workers was used, with which demographic variables, knowledge, attitudes, practices and risk perception were collected. The data were analyzed through the SPSS statistical program. For the univariate analysis, descriptive statistics were used to represent the data expressed in frequencies, percentages and tables. It was observed that 52.9% of the workers had knowledge about zoonotic diseases, 74.4% had positive attitudes, 66.9% implemented positive practices and 52.9% perceived the risk. Less than 75% of the workers surveyed had optimal knowledge, attitudes, practices and perceptions of risk, which is worrying considering their constant exposure to zoonotic diseases, that is why multisectoral educational strategies should be implemented concerning these pathologies and their preventive measures to improve this situation

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