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This study describes extracellular biosynthesis of cadmium sulfide quantum dots by Fusarium oxysporum f. sp. lycopersici. Mycelia was incubated with a cadmium sulfate solution at 30°C and after 12 days the mixture became yellow, then the biomass was discarded through paper filtration. The filtrate containing extracellular cadmium sulfide quantum dots displayed increased UV-Vis absorption from 300 - 500 nm and fluorescence at 520 nm which was not shown when incubated without cadmium sulfide, thus indicating the presence of biologically synthesized quantum dots. Transmission electron microscope analysis of biologically synthesized quantum dots evinced individual 2 - 6 nm diameter circular nanoparticles of uniform size. Energy dispersive spectroscopy confirmed the presence of S and Cd. Additionally, this study showed the relevance in the use of positive and negative controls when evaluating the biosynthesis of CdS quantum dots using UV-Vis and fluorescence spectrophotometry.

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Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) is one of the most damaging pests in maize crops. In order to manage it, synthetic insecticides such as diamides, neonicotinoids, and pyrethroids are used, but they present a risk for humans and the environment. Investigations of safer alternatives include the use of natural extracts. Thus, this research evaluated the effects of chloroform extract (CHCl3Sc) (5000, 4000, 2000, 1000, and 500 ppm) on aerial parts of Salvia connivens and of nonanal and pyrocatechol (1000, 600, 400, and 80 ppm) on S. frugiperda mortality, duration of the larva and pupae phases, and pupae weight after 24 h. The second instars of S. frugiperda larvae were fed an artificial diet incorporating the extract and compounds. The CHCl3Sc had insecticidal activity against S. frugiperda, showing an LC50 of 1504 ppm. Insectistatic activity began at 1000 ppm, increasing pupal and larval duration in 7.6 and 1.4 days, respectively. Pyrocatechol and nonanal were found in this extract. The first did not have any significant difference in larval or pupal mortalities. On the other hand, insectistatic activity was shown at 500 ppm, increasing the larval duration by 1.7 days compared with the control. In the case of nonanal, the insecticide activity was LC50 of 200 ppm, and insectistatic activity started at 80 ppm, increasing larval duration by 3.2 days compared with the control and reducing pupal weight by 3.4%. The results show that chloroformic extract had insecticidal and insectistatic activities against S. frugiperda; nonanal was an aldehyde compound present in this extract, which confers insecticidal and insectistatic activities against this pest.

El tratamiento biológico es el más utilizado para las aguas residuales domésticas. El reactor de lecho fijo es una biopelícula de microorganismos capaces de degradar la materia orgánica, y es una alternativa eficiente en comparación con los sistemas convencionales, ya que aumenta la superficie de contacto entre el microorganismo y la materia orgánica. El presente trabajo se centra en la adaptación, aclimatación y uso de lodo activado para la formación de una biopelícula en un biorreactor para el tratamiento de efluentes domésticos con un soporte PET; se comprobó que dicho material es factible para ser implementado como medio de soporte. El sistema de lecho fijo se mantuvo en operación durante 150 días, utilizando agua residual doméstica como sustrato, y evaluando la eficiencia del reactor por medio de parámetros de calidad de agua. La diversidad microbiana se evaluó por análisis de ARNr 16S. Las eficiencias de remoción de la Demanda Química de Oxigeno (DQO) y Demanda Bioquímica de Oxigeno (DBO) fueron mayores del 90 % y se logró la neutralización del efluente con características alcalinas. El tiempo de tratamiento fue de 4 h.  Se identificaron 11 Phylum bacterianos correspondientes para biopelícula y 8 en suspensión, donde los principales grupos bacterianos fueron Proteobacterias, Bacteroidetes y Firmicutes. El tiempo de tratamiento disminuyó en un 50 % respecto a los sistemas convencionales. La identificación de los Phylum permite comprender mejor la complejidad de las estructuras bacterianas en aguas residuales y como interviene en la eficiencia de los procesos del tratamiento de aguas residuales.

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Sargassum spp. affects the Caribbean shores; thus, its remotion or valorization is a priority. This work aimed to synthesize a low-cost magnetically retrievable Hg+2 adsorbent functionalized with ethylenediaminetetraacetic acid (EDTA) based on Sargassum. The Sargassum was solubilized to synthesize by co-precipitation a magnetic composite. A central composite design was assessed to maximize the adsorption of Hg+2. The solids yield magnetically attracted mass, and the saturation magnetizations of the functionalized composite were 60.1 ± 17.2%, 75.9 ± 6.6%, and 1.4 emu g−1. The functionalized magnetic composite yielded 29.8 ± 0.75 mg Hg+2 g−1 of chemisorption after 12 h, pH 5, and 25 °C achieving 75% Hg+2 adsorption after four reuse cycles. Crosslinking and functionalization with Fe3O4 and EDTA created differences in surface roughness as well as the thermal events of the composites. The Fe3O4@Sargassum@EDTA composite was a magnetically recovered biosorbent of Hg2+.