The modulation in the synthesis parameters of layered manganese oxides allowed us to produce materials with different AC conductivities. These conductivities were correlated with the catalytic performance of the materials in the decomposition of methylene blue, as a model of electron transfer reactions. The manganese oxides were prepared by thermal reduction of KMnO4 at 400°C and 800°C where one sample was heated at 1°C/min and the other was heated at 10°C/min. The materials were characterized by atomic absorption, average oxidation states of manganese, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The results indicate that, by increasing the synthesis temperature, both the lamellar arrangement and the crystal size increased, while the Mn4+ amount in the material decreased. Furthermore, it was observed that as the conductivity increases for the materials, the catalytic performance also increases. Therefore, a direct correlation between the conductivity and catalytic performance can be established. For example, the layered manganese oxides material synthesized at 400°C, using a heating rate of 10°C/min, showed the highest AC conductivity and had the best performance in the degradation of methylene blue. Finally, we propose a general mechanism for understanding how manganese oxides behave as catalysts that produce oxidizing species from H2O2 which degrades methylene blue. Our proposed mechanism takes into consideration the state of aggregation of the catalyst, the availability of Mn4+, and the electrical conductivity.

Heavy metals are dangerous pollutants of water and soil coming, in first place, from anthropogenic activity. Lead (Pb) can be accumulated in soil surface and it is easily take by plants inducing many symptoms of toxicity. Several research suggests that Pb toxicity leads to the induction of key enzymes of antioxidant defense system in tomato plants. This mini review will show the influence of Pb in some enzymes of tomato oxidative system focusing in the analysis of protein content and the enzymes glutathione reductase and superoxide dismutase in different parts of the plant (leaves and stem), some genes related to the oxidative stress of tomato were also study.

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The genus Beauveria comprises a cosmopolitan teleomorphic and anamorphic group of ento-mopathogenic fungi. The aim of this study was to characterize a new isolate of Beauveria spp. and compare it to the LBB-1 commercial strain. The isolate was collected from the ant Atta insularis and adults of the coffee borer, respectively. It was cultivated on solid SDAY medium enriched with 1% yeast extract. The biological effectiveness of the isolate was determined on C. formicarius. DNA was isolated using the CTAB method and an internal transcribed spacer (ITS1, ITS4) were used as primers for amplification. The consensus sequence obtained was deposited in GenBank (MK246940) and used for phylogenetic analysis. This isolate showed differences in morphological characteristics; however, it showed low genetic variability regarding worldwide isolates of B. bassiana. Concerning its biological effectiveness, the isolate demonstrated to be virulent on the phytophagous adults, producing 50% mortality. Four clades were identified and the polytomous topography recovered for clade 1 indicates high genetic similarity (99-96%) with Beauveria bassiana from several countries. The morphological and molecular characterization made it possible to accurately identify the new isolate as Beauveria bassiana. The identified specie is another possibility for integrated pest management in Cuba and Mexico.