Promoción del crecimiento en plantas de Capsicum annuum por nanopartículas de óxido de zinc

The applications that nanotechnology (NT) has on agriculture systems are diverse and promising because they have the potential to contribute in maintaining its productivity and efficiency by reducing costs and the quantity of synthetic agrochemicals employed. For instance, it is important to emphasize that by means of NT it is possible to develop encapsulated nanopesticides, stabilization of biopesticides and slow-release fertilizers. Nanoparticles of zinc oxide and silver are studied for their potential as antimicrobial, nanofertilizers and growth promoters of agricultural plants. Therefore, the aim of this study was to evaluate the effect of pure zinc oxide nanoparticles (ZnONPs) and ZnONPs with silver (ZnONPs + Ag) on growth of C. annuum plants. The sol-gel method was used to study the synthesis and characterization of NPs. Foliar application of ZnONPs to pepper plants was done manually once a week. The experimental design was completely at random with four treatments and five repetitions. Data collected were analyzed by ANOVA and Tukey's multiple range tests (p ≤ 0.05). Compared to control plants without the application of ZnONPs, treatments exposed to the application of ZnONPs + Ag (2.5%), were those that had a significant higher shoot and root growth, as well greater biomass production, with higher values of height (16.8%), leaf area (30.3%), total biomass production (59.5%), root dry biomass (112.5%), stem dry biomass (76%) and root length (24.4%). As compared to control plants, those treated with ZnONPs + Ag (2.5%) reported a quantitative increase of chlorophyll index (8%) and leave number (32.6%). The biological effect of the applied NPs, could be related to the zinc activity as a precursor in the production of auxins, which in turn could promote cell division and elongation, as well by its influence on the reactivity of indol acetic acid, which acts as hormonal phytoestimulant. Also ZnONPs might be involved in the biosynthesis of cytokinins and gibberellins; as well on the induction of greater activity of antioxidant enzymes.Las aplicaciones de la nanotecnología (NT) en los sistemas agrícolas son diversas, ofreciendo el potencial para mejorar significativamente su productividad y eficiencia al reducir costos y cantidades de agroquímicos aplicados. Las nanopartículas (NPs) metálicas de óxido de zinc, cobre y fierro, ya sean puras o mezcladas con plata, están siendo estudiadas globalmente por su potencial agrícola como promotores de crecimiento, nanofertilizantes y antimicrobiales. Considerando lo antes señalado, el objetivo de este trabajo fue evaluar el efecto de NPs de óxido de zinc puras (NPsZnO) y con plata (NPsZnO+Ag) en el crecimiento de plantas de chile (Capsicum annuum). La síntesis y caracterización de las NPs mencionadas se realizó mediante el método de sol-gel. La aplicación foliar de las NPs a las plantas se hizo semanalmente; el diseño experimental empleado fue completamente al azar con cuatro tratamientos y cinco repeticiones. Los datos obtenidos se procesaron mediante un análisis de varianza y prueba de rango múltiple Tukey (p ≤ 0.05). Los resultados señalan que las plantas expuestas a la aplicación de NPsZnO + Ag al 2.5% en peso, tuvieron significativamente mayor crecimiento y producción de biomasa en comparación con las plantas del tratamiento control, mostrando valores superiores de altura (16.8%), área foliar (30.3%), producción de biomasa total (59.5%), biomasa seca de raíz (112.5%), biomasa seca de tallo (76%) y longitud de raíz (24.4%). También se observó un incremento del índice de clorofila (8%) y número de hojas (32.6%). El efecto promotor de crecimiento de las NPs aplicadas podría atribuirse a la actividad del zinc como precursor de la producción de auxinas que promueven división y elongación celular; así como por su influencia en la reactividad del ácido indolacético, el cual actúa como fitoestimulante hormonal. También puede ser factible que las NPs estudiadas estén involucradas en la biosíntesis de citoquininas y giberelinas; así como en la inducción de mayor actividad de enzimas antioxidantes

Nanomaterials and catalysis for green chemistry

Recently, green chemistry for the development of sustainable production systems requires tremendous research efforts on the design of catalysts through resource-efficient ways. The improvement of their catalytic performances is a key goal in modern society. Several approaches using environmentally friendly chemicals and materials for less hazardous synthesis and catalysis were analyzed. In this review, we focus on the synthesis of nanomaterials and catalytic applications to reduce the environmental impact, especially, by reducing waste, solvents, precursors, and derivatives. In addition, we highlight the special efforts toward the use of renewable feedstocks and their applications as well as the synthetic routes to develop nanocatalysts using a greener chemistry. © 2020 Elsevier B.V

Effect of the sulfur and fluorine concentration on physical properties of CdS films grown by chemical bath deposition

Undoped and F-doped CdS thin films were grown on glass slides by chemical bath deposition using thiourea, cadmium acetate and ammonium fluoride as sulfur, cadmium, and fluorine sources, respectively. Undoped CdS films were deposited varying the concentration of thiourea. Once the optimal thiourea concentration was determined, based on the crystalline quality of the samples, this concentration was maintained and ammonium fluoride was added at different concentrations in order to explore the effect of the F nominal concentration on properties of CdS films. Undoped and F-doped CdS films were characterized by X-ray diffraction, UV–Vis, room temperature photoluminescence, and four probe resistivity measurements. Results showed highly transparent F-doped CdS films with strong PL and low resistivity were obtained. Keywords: CdS films, F-doped CdS films, Chemical bath deposition, Optical properties, Room temperature photoluminescenc