Photocatalytic Decomposition of Metoprolol and Its Intermediate Organic Reaction Products: Kinetics and Degradation Pathway

High purity metoprolol prepared by neutraliza-tion of an aqueous solution of metoprolol tartrate is efficiently mineralized to CO2 and water by photocatalysis with TiO2, UV light and a constant flow rate of oxygen. Since the tartrate anions were eliminated, all the HO•generated by photocatalysis reacted efficiently with the aromatic part of the medication. The reaction pathway includes two routes of degradation. The first one includes the transformation of metoprolol to hydroquinone via formation of 4-(2-methoxyethyl)phenol, 2-(4-hydroxyphe-nyl)ethanol and 4-hydroxybenzaldehyde. Metoprolol is also degraded directly to hydroquinone. Then, this aro-matic compound is oxidized to 1,2,4-benzenetriol, which is rapidly oxidized to low molecular weight organic acids before being completely mineralized to CO2 and water. Kinetic studies indicated that the initial reaction rate of the degradation of metoprolol, 4-(2ethoxyethyl)phenol, 2-(4-hydroxyphenyl)ethanol and 4-hydroxybenzaldehyde is described by the LH-HW model

Photocatalytic hydrogen evolution using bi-metallic (Ni/Pt) Na2Ti3O7 whiskers: Effect of the deposition order

Photocatalytic hydrogen production through ethanol photo-reforming using Na2Ti3O7 whiskers increases if the sodium titanate is decorated with well-known metallic catalysts such as Ni and Pt. Whereas wet impregnation with nickel gives only a slight increase in the activity, photo-deposition of Pt increased the H2 production by more than one order of magnitude. Through the combination of both co-catalysts (Ni and Pt) a superior performance in terms of H2 production is further observed. However, hydrogen yield is largely enhanced (almost three-fold), up to 778 μmol·g−1·h−1, if the Pt is photo-deposited on the surface of the catalyst before wet impregnation with Ni species (NTO/Pt/Ni) compared to H2 yield (283 μmol·g−1·h−1) achieved with the catalyst prepared in the reverse order (NTO/Ni/Pt). Structural, morphological, optical, and chemical characterization was carried out in order to correlate physicochemical properties with their photocatalytic activity. The X-ray photoelectron spectroscopy (XPS) results show a higher concentration of Pt2+ species if this metallic layer is under the nickel oxide layer. Moreover, X-ray diffraction patterns (XRD) show that Na2Ti3O7 surface is modified for both metal decoration processes

Sodium N-methyldithiocarbamate impact on soil bacterial diversity in greenhouse tomato (Solanum lycopersicum L.) crop

The constant use of sodium N-methyldithiocarbamate (metam sodium: MS) in protected agriculture in México has attracted the attention of researchers and producers on their effects on the environment. The objective of this study was to evaluate the impact of MS on the bacterial community structure in an agricultural soil with tomato crop (Solanum lycopersicum L.) considering the different phenological stages of the crop. The experiment was carried out in a greenhouse, with a completely randomized block design with two treatments: 1) without MS and 2) with application of 400 L·ha-1 of MS. For the determination of the bacterial structure, the biodiversity indexes of richness (S), diversity (H') and equity (J'), identification of operational taxonomic units (OTU) were used through the T-RFLP technique. Application of MS in soil showed no significant effect on bacterial richness. However, the application of MS does alter the structure of the bacterial community (H' and J') in each of the tomato phenological stages. Finally, future studies which include the evaluation of the effects of MS on the physiology of intensive crops and functions in the different soil types are need.The constant use of sodium N-methyldithiocarbamate (metam sodium: MS) in protected agriculture in México has attracted the attention of researchers and producers on their effects on the environment. The objective of this study was to evaluate the impact of MS on the bacterial community structure in an agricultural soil with tomato crop (Solanum lycopersicum L.) considering the different phenological stages of the crop. The experiment was carried out in a greenhouse, with a completely randomized block design with two treatments: 1) without MS and 2) with application of 400 L·ha-1 of MS. For the determination of the bacterial structure, the biodiversity indexes of richness (S), diversity (H') and equity (J'), identification of operational taxonomic units (OTU) were used through the T-RFLP technique. Application of MS in soil showed no significant effect on bacterial richness. However, the application of MS does alter the structure of the bacterial community (H' and J') in each of the tomato phenological stages. Finally, future studies which include the evaluation of the effects of MS on the physiology of intensive crops and functions in the different soil types are need

Antimicrobial and antioxidant properties of byproduct extracts of mango fruit

Byproducts of fruit processing could have higher content of phenolic compounds that can act as antimicrobial and antioxidant agents. In this context, the main objective of this study was to obtain extracts from peel, seed, and unused flesh of Haden, Ataulfo and Tommy Atkins mango varieties, in order to measure their antioxidant and antimicrobial properties. The extraction was performed using different methods, such as methanolic-polar, methanolic-non-polar, ethanolic-polar, ethanolic-non-polar and water infusion. The total phenolic content of the ethanolic-non-polar extract from seed of mango Haden showed 875.06 mg/g, DPPH EC50: 0.04 mg/mL, cau-sing a 100 % inhibition of bacteria pathogens applying 25 mg/mL and inhibition of 89.78 % against Alternaria applying 6.25 mg/mL. The flesh always showed the lowest content and bioactivity of the tested parameters. These results demonstrate the antimicrobial and antioxidant potential uses of fruit byproducts as sources of bioactive compounds

Sistema de aprendizaje automático para la detección de neumonía

"En este trabajo se presenta una herramienta para la detección de neumonía en radiografías de rayos-X, utilizando aprendizaje automático, esta herramienta es un software que está programada totalmente en Python utilizando el entorno de desarrollo Spyder de Anaconda. Para realizar este proyecto, se descargaron bancos de imágenes de radiografías de rayos-X a las cuales se les aplica un preprocesamiento para estandarizar las imágenes, este consiste en la mejora de contraste aplicando ecualización del histograma, además las imágenes son recortadas de tal manera que se obtenga únicamente el área de los pulmones y se redimensionan a un tamaño de 256x256, posteriormente se define un conjunto de prueba y un conjunto de entrenamiento etiquetados, sobre este último, se aplica análisis de componentes principales (PCA), los pesos resultantes de la proyección de las imágenes sobre los componentes principales se normalizan y se seleccionan las características que mejor separan las dos clases"

Heterojunctions for Photocatalytic Wastewater Treatment: Positive Holes, Hydroxyl Radicals and Activation Mechanism under UV and Visible Light

Forming heterojunctions by coupling two or more semiconductors is an important strategy to develop stable and efficient photocatalysts able to operate both under near-UV and visible light. Five novel heterojunction sys-tems were synthesized in the present study, using a modified sol-gel method: Bi2Mo3O12/TiO2, ZnFe2O4/TiO2, FeTiO3/TiO2, WO3(US)/TiO2 and WO3/TiO2. These heterojunction semiconductors were characterized by us-ing XRD, SEM and EDX, UV–Vis diffuse reflectance spectroscopy and BET. Their photocatalytic activities were evaluated using methyl orange (MO) degradation under both near-UV and visible light. From the various het-erojunctions developed, the WO3(US)/TiO2 photocatalyst was the one that showed the highest photocatalyticefficiency with this being assigned to the formation of a double heterojunction involving anatase, rutile and monoclinic WO3 phases. On this basis, a photocatalyst activation mechanism applicable to near-UV and visible light irradiation was proposed. This mechanism explains how the photogenerated electrons (e–) and positive holes (h+) can be transferred to the various phases. As a result, and given the reduced holes and electron recom-bination surface, hydroxyl radicals found were more abundant. To confirm this assumption, hole formation in the valence band was studied, using hole-scavenging reactions involving ion iodine (I–), while hydroxyl radical production used fluorescence spectroscopy