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168 resultados, página 6 de 10

Carbamazepine degradation by visible-light-driven photocatalyst Ag3PO4/GO: Mechanism and pathway

Guanhan Chen Wenyi Dong Hongjie Wang Zilong Zhao Feng Wang Feifei Wang César Nieto Delgado (2022, [Artículo])

"Carbamazepine (CBZ), as one of the most frequently detected pharmaceuticals, is of great concern due to its potential impact on the ecosystem and human health. This study provides an effective approach to remove CBZ by using photocatalyst silver phosphate combined with graphene oxide (Ag3PO4/GO) under visible irradiation. The morphology, composition, and optical properties of Ag3PO4/GO were characterized employing SEM, XRD, and DRS. Graphene oxide could improve the visible-light utilization and promote electron's charge to enhance the photocatalytic performance of Ag3PO4/GO. With the optimal reaction condition of 5.86 mW/cm(2) light intensity, 15-25 degrees C temperature, 5-7 pH, and 0.5 mg/L catalytic dosages, 5 mg/L CBZ could be completely degraded in 30 min, and the apparent rate constant could reach 0.12 min(-1). Additionally, the radical trapping experiments indicated center dot OH and O-2(-)center dot were the main reactive oxygen species employed to eliminate CBZ. The decay pathways of CBZ had been proposed accordingly, and the main product was the low-molecular products. (C) 2021 The Authors. Published by Elsevier B.V. on behalf of Chinese Society for Environmental Sciences, Harbin Institute of Technology, Chinese Research Academy of Environmental Sciences."

Carbamazepine Ag3PO4/GO Visible light Photocatalysis INGENIERÍA Y TECNOLOGÍA INGENIERÍA Y TECNOLOGÍA

The input reduction principle of agroecology is wrong when it comes to mineral fertilizer use in sub-Saharan Africa

Gatien Falconnier Marc Corbeels Frédéric Baudron Antoine Couëdel leonard rusinamhodzi bernard vanlauwe Ken Giller (2023, [Artículo])

Can farmers in sub-Saharan Africa (SSA) boost crop yields and improve food availability without using more mineral fertilizer? This question has been at the center of lively debates among the civil society, policy-makers, and in academic editorials. Proponents of the “yes” answer have put forward the “input reduction” principle of agroecology, i.e. by relying on agrobiodiversity, recycling and better efficiency, agroecological practices such as the use of legumes and manure can increase crop productivity without the need for more mineral fertilizer. We reviewed decades of scientific literature on nutrient balances in SSA, biological nitrogen fixation of tropical legumes, manure production and use in smallholder farming systems, and the environmental impact of mineral fertilizer. Our analyses show that more mineral fertilizer is needed in SSA for five reasons: (i) the starting point in SSA is that agricultural production is “agroecological” by default, that is, very low mineral fertilizer use, widespread mixed crop-livestock systems and large crop diversity including legumes, but leading to poor soil fertility as a result of widespread soil nutrient mining, (ii) the nitrogen needs of crops cannot be adequately met solely through biological nitrogen fixation by legumes and recycling of animal manure, (iii) other nutrients like phosphorus and potassium need to be replaced continuously, (iv) mineral fertilizers, if used appropriately, cause little harm to the environment, and (v) reducing the use of mineral fertilizers would hamper productivity gains and contribute indirectly to agricultural expansion and to deforestation. Yet, the agroecological principles directly related to soil fertility—recycling, efficiency, diversity—remain key in improving soil health and nutrient-use efficiency, and are critical to sustaining crop productivity in the long run. We argue for a nuanced position that acknowledges the critical need for more mineral fertilizers in SSA, in combination with the use of agroecological practices and adequate policy support.

Manure Crop Yields Smallholder Farming Systems Environmental Hazards CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA BIOLOGICAL NITROGEN FIXATION LEGUMES NUTRIENT BALANCE SOIL FERTILITY AGROECOLOGY YIELD INCREASES LITERATURE REVIEWS

Lo fantástico más allá de la vacilación: la representación mimética del miedo en dos cuentos de Bioy Casares y Cortázar

ANDREAS KURZ ESSMEISTER (2014, [Artículo])

El artículo revisa algunos conceptos y definiciones de lo fantástico literario y pretende diferenciarlo de lo postulado por el realismo mágico y lo real maravilloso. Se proponen como textos clave al respecto el libro de Franz Roh que da nombre al realismo mágico, la historia de la literatura fantástica por H. P. Lovecraft, así como la tesis de 'das Unheimliche' de S. Freud. A manera de hipótesis establecemos el carácter mimético de la literatura fantástica que en primer lugar representa el miedo. Nos dirigimos contra la idea de la vacilación expuesta por Todorov. Finalmente pretendemos mediante el análisis de dos cuentos canónicos testar nuestra hipótesis.

CIENCIAS SOCIALES Literatura fantástica Realismo mágico Real maravilloso Adolfo Bioy Casares (1914-1999) Julio Cortázar (1914-1984)

EFECTOS DE LA CONFORMACIÓN ESTRUCTURAL DE UN SUBSTRATO EN LA EMISIÓN DE FLUORESCENCIA POLARIZADA: ANÁLISIS DE FACTIBILIDAD TÉCNICA PARA EL DESARROLLO DE UN SENSOR ÓPTICO CON APLICACIONES BIOMÉDICAS

Danay Hernández (2023, [Tesis de doctorado])

"La celulosa, localizada en las paredes celulares de las plantas, es uno de los polímeros más prevalentes en la naturaleza y puede ser obtenida mediante diversos métodos, incluida la síntesis de cierto tipo de bacterias. Este polímero da origen a un material específico denominado nanocelulosa, clasificado según su estructura en nanocristales (CNC, por sus siglas en inglés, Cellulose Nano-Crystals), nanofibras (CNF, por sus siglas en inglés, Cellulose Nano-Fibers) y celulosa bacteriana (BC, por sus siglas en inglés, Bacterial Cellulose). En el ámbito biomédico, los nanocristales de celulosa han tenido un impacto significativo debido a su biocompatibilidad y sostenibilidad, destacándose en aplicaciones como la fabricación de apósitos para el tratamiento y monitoreo de la cicatrización de heridas, un proceso que generalmente se evalúa objetivamente por especialistas."

Celulosa Nanocristales Biosensores Luz polarizada Fluorescencia Cristal líquido CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA

Evaluation of sunlight and humidity protection of a bioherbicide for Eichornia crassipes biocontrol

MARICELA MARTINEZ JIMENEZ MARIA ANTONIETA GOMEZ BALANDRA MARIA DEL PILAR SALDAÑA FABELA (2015, [Artículo])

C. piaropi (Cercospora piaropi) and A. zonatum (Acremonium zonatum) have proved to be effective in reducing water hyacinth growth. However, efficacy of these fungi in field is limited by the effect of solar UV (ultraviolet) light and desiccation. In this study, three compounds used as sunscreens and one seed plant that produce mucilage were tested for their effects on the infection produced by C. piaropi and A. zonatum inoculum under laboratory and field conditions. In laboratory conditions, TiO2 (titanium dioxide) and metamucil did not inhibit C. piaropi and A. zonatum viability. Moreover, the addition of TiO2 and metamucil to the inoculum suspension increased fungi infection. The protective effect of TiO2 and metamucil was more evident when the inoculum suspension was applied 4 h before sunset. These results suggest that addition of TiO2 and metamucil provides necessary humidity and solar protection for increasing C. piaropi and A. zonatum infection on water hyacinth plants.

Lirios acuáticos Radiación solar Dióxido de titanio C. piaropi A. zonatum BIOLOGÍA Y QUÍMICA

Modelo de optimización de recursos para un distrito de riego

Model for the optimization of resources for an irrigation district

DAVID ORTEGA GAUCIN ENRIQUE MEJIA SAENZ ENRIQUE PALACIOS VELEZ LUIS RENDON PIMENTEL ADOLFO ANTENOR EXEBIO GARCIA (2008, [Artículo])

Mediante el uso de técnicas de programación lineal se desarrolló un modelo de optimización de recursos hídricos para el distrito de riego 005, localizado en Delicias, Chihuahua,México. El modelo planteado permitió estimar la superficie de riego y el patrón de cultivos óptimo para incrementar los beneficios netos de los productores. Se analizaron cuatro escenarios posibles, tomando en cuenta la disponibilidad de volúmenes clave en las fuentes de abastecimiento de agua, así como dos eficiencias de conducción de la red de canales. Los resultados indicaron que la superficie sembrada en el distrito fue de 70 459 ha. La superficie estimada por el modelo fue menor de 9643 ha con respecto a la superficie regable actualmente; por lo cual se concluye que es conveniente establecer estrategias para que, en situaciones próximas, la superficie excedente sea desincorporada del distrito de riego, o bien, reducir la concesión de agua con la finalidad de lograr la sustentabilidad de los módulos.

Using linear programming techniques, a model for optimizing water resources was developed for the Irrigation District 005, located in Delicias, Chihuahua, Mexico. The proposed model allowed estimation of the irrigation area and optimal cropping pattern needed to increase net benefits for growers. Four possible scenarios were analyzed, considering the availability of key volumes in water supply sources, as well as two conduction efficiencies for the network of irrigation channels. The results indicated that the area cultivated in the Irrigation District was 79 459 ha. The area estimated by the model was 9643 ha less than the area currently irrigation. It is thus concluded that it would be recommendable to establish strategies for withdrawing the excess area from the Irrigation District or for reducing water concessions in order to achieve sustainability of the modules.

Agricultura Productividad agrícola Programas de computación Programación lineal INGENIERÍA Y TECNOLOGÍA