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Hydrogen production by tailoring the brookite and Cu2O ratio of sol-gel Cu-TiO2 photocatalysts

MARIANA HINOJOSA REYES ROBERTO CAMPOSECO SOLIS Rodolfo Zanella VICENTE RODRIGUEZ GONZALEZ (2017)

"Cu-TiO2 photocatalysts were prepared by the sol-gel method. Copper loadings from, 1.0 to 5.0 wt % were used. The materials were annealed at different temperatures (from 400 to 600 °C) to study the formation of brookite and copper ionic species. The photocatalysts were characterized by X-ray diffraction, UV–vis, Raman and XPS spectroscopies, H2-temperature programmed reduction (TPR), N2 physisorption, and SEM–EDS to quantify the actual copper loadings and characterize morphology. The photocatalysts were evaluated during the hydrogen photocatalytic production using an ethanolic solution (50% v/v) under UV and visible radiation. The best hydrogen production was performed by Ti-Cu 1.0 with an overall hydrogen production that was five times higher than that obtained with photolysis. This sample had an optimal thermal treatment at 500 °C, and at this temperature, the Cu2O and brookite/anatase ratio boosted the photocatalytic production of hydrogen. In addition, a deactivation test was carried out for the most active sample (TiO2-Cu 1.0), showing unchanged H2 production for three cycles with negligible Cu lixiviation. The activity of hydrogen-through-copper production reported in this research work is comparable with the one featured by noble metals and that reported in the literature for doped TiO2 materials."

Article

Cu-TiO2 Water splitting Cu2O Anatase brookite ratio Copper lixiviation Cyclic H2 production BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA

Gold, Silver, and Copper phytoextraction by helianthus annuus sunflower grown on mine tailings amended with plant growth regulators and cyanide

Werner Rubio Carrasco Jeiry Toribio Jiménez (2014)

In 1998, it was reported that plants of Brassica juncea (L) Czern. Could be forced to accumulate Au to concentrations as high as 57 mg/kg of dry matter after suitable treatment of the substrate in which they were growing

Phytoextraction has been suggested as aviable technique for gold recovery from some areas of mine tailings and mineralized soils. Plant Growht Regulators have been used due to their potential to improve rates of metal phytoextraction.

Article

Rooting Phytoextraction Mine tailings Helianthus annuus gold Copper Silver BIOLOGÍA Y QUÍMICA QUÍMICA

Bone copper content in sheep in relation to their drinking water source

ARTURO FRANCISCO CASTELLANOS RUELAS (2017)

The aim was to estimate the Cu content in the bones of grazing sheep and relate it to their drinking water. Cu was analyzed by taking bone biopsies. Samples from the twelfth rib were taken in 107 animals and water samples were collected from forty wells in the same farms located in four agroecological areas in Yucatán state, Mexico. Cu was analyzed by atomic absorption. Data were analyzed using the least squares method. Cu content in bone tissue was: weaned 0.66 a; Females prior to rst gestation 0.57 b and ewes 0.64 a mg/kg-1. Normal content in bone is 2-3 mg/kg-1, indicating a de ciency in the animals. Cu in water was 0.15 ab, 0.12 b, 0.16 ab and 0.19 a mg/L-1 in the center, east, west and south part of the State respectively. Cu concentration in water for animal consumption was low. In conclusion, Cu de ciency was diagnosed in grazing sheep that could be associated with the low Cu content in the drinking water.

Article

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA copper bone biopsy grazing

Gold, silver, and copper phytoextraction by helianthus annuus l. (sunflower) grown on mine tailings amended with plant growth regulators and cyanide

Leopoldo Partida Ruvalcaba Werner Rubio Carrasco Jeiry Toribio Jiménez (2014)

Phytoextraction has been suggested as aviable technique for gold recovery from some areas of mine tailings and mineralized soils. Plant Growth Regulators have been used due to their potential to improve rates of metal phytoextraction. However, no studies have specifically described the efficacy of exogenous plant growth regulators on the process of gold phytoextraction for plants grown in mine tailings.

Article

Rooting Phytoextraction Mine tailings Helianthus annuus L Gold Copper Silver CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO

Producción de biogás a diferentes concentraciones de cobre en un cultivo in vitro con bacterias ruminales de ovino, caprino y bovino

JULIO CESAR AYALA FIGUEROA (2014)

Tesis (Maestría en Ciencias, especialista en Ganadería).- Colegio de Postgraduados, 2014.

El estudio tuvo como objetivo evaluar el efecto de diferentes concentraciones de cobre en el pH, nitrógeno amoniacal (N-NH3), ácidos grasos volátiles (AGV), digestibilidad in vitro de la materia seca (DIMS), contenido de purinas y biogás total en medios de cultivo in vitro usando inóculos ruminales de ovinos, caprinos y bovinos. Los animales donantes de los inóculos fueron canulados en rumen y alimentados a libre acceso con alfalfa achicalada. Se elaboraron medios de cultivo, usando como sustrato 0.5 g de alfalfa molida a un tamaño de partícula de 1 mm, a los cuales se adicionó su respectivo tratamiento de cobre (0, 5, 10, 20, 40, 60 y 80 ppm), en tres series con base al inóculo ruminal (ovino, caprino o bovino), y nueve repeticiones por tratamiento. La producción de biogás total se analizó a las 12, 24, 48 y 72 h, mediante un modelo no lineal con el Software SigmaPlot y el resto de las variables se analizaron mediante un diseño completamente al azar y las medias de tratamientos se compararon con la prueba de Tukey. La adición de niveles de 10 ppm de Cu, incrementaron (p<0.05) la producción de biogás total al usar inóculos ruminales de ovinos y caprinos, relacionándose con mayor actividad bacteriana y mayor (p<0.05) degradación de la materia seca. Pero al incrementar la concentración de cobre por arriba de 20 ppm disminuyó (p<0.05) la producción de biogás total en sistemas in vitro, independientemente de la fuente de inoculo ruminal, y de manera específica, el líquido ruminal de bovinos presenta la menor actividad microbiana reflejándose en una producción de biogás más baja (p<0.05). El pH de los medios de cultivo no cambia (p>0.05) al adicionar niveles de 0 a 20 ppm de cobre o al inocular con líquido ruminal de ovinos, caprinos o bovinos. Sin embargo la concentración de nitrógeno amoniacal es alta (p<0.05) cuando se adiciona a los medios de cultivo 5 ppm de cobre y entre los inóculos evaluados, el de caprinos mostró la mayor (p<0.05) producción de este metabolito. Asimismo, la mayor (p<0.05) producción de ácidos grasos volátiles se registró al adicionar entre 5 y 10 ppm de cobre cuando se usaron inóculos de ovinos o bovinos, pero cuando el inoculo fue de caprino no existió diferencia (p>0.05) entre los niveles de cobre evaluados (0 a 20 ppm). Niveles crecientes de cobre en los medios de cultivo se relacionaron con una disminución (p<0.05) de acético e incremento de propiónico y butírico. La fuente de inóculo no fue consistente en los cambios observados en la fermentación en el sistema in vitro evaluado con diferentes niveles de Cu. Niveles entre 5 y 10 ppm de cobre son sugeridos para producir mejoras metabólicas en la fermentación ruminal. _______________ BIOGAS PRODUCTION AT DIFFERENT COPPER CONCENTRATIONS ON IN VITRO CULTURE WITH SHEEP, GOATS AND CATTLE RUMINAL BACTERIA. ABSTRACT: The aim of this study was to evaluate the effect of different copper concentrations on pH, ammonia (N-NH3), volatile fatty acids (VFA), in vitro dry matter digestibility (IVDMD), purines, total biogas on in vitro culture, using rumen liquid from sheep, goats and cattle. Animal donors of the inoculants were cannulated in the rumen and fed ad libitum with hay alfalfa. Culture media was prepared using 0.5 g of hay alfalfa as substrate, ground to a particle size of 1 mm, with its respective treatment of copper (0, 5, 10, 20, 40, 60 and 80 ppm) was added, into three series based on the ruminal inoculum (sheep, goats or cattle), and nine replicates per treatment. The biogas production was analyzed at 12, 24, 48 and 72 h, using a nonlinear model with the SigmaPlot Software and the other variables were analyzed using a completely randomized design and the treatment means were compared with Tukey test. Addition of 10 ppm of Cu, increased (p <0.05) total biogas production using rumen inoculum from sheep and goats, and this was related to increased bacterial activity and increased (p <0.05) dry matter degradation. Also when copper concentration increasing above 20 ppm biogas production in vitro decreased (p <0.05) regardless of the source of ruminal inoculum, and, specifically bovine rumen fluid has the lowest activity microbial reflected in a lower biogas production (p<0.05). Culture media pH no changes (p>0.05) by adding copper levels of 0 to 20 ppm or inoculated with rumen fluid of sheep, goats or cattle. However, nitrogen concentration is high (p <0.05) when added to the culture media 5 ppm of copper, and goats inoculum showed higher (p <0.05) production of this metabolite. Also, the higher (p<0.05) production of volatile fatty acids was recorded by adding 5 to 10 ppm of copper when inoculum from sheep and cattle were used, but when the goats inoculum was used there was no difference (p> 0.05) between 0 to 20 ppm of copper treatments. Increasing levels of copper in the culture media were associated with a decrease (p <0.05) of acetic and increased of propionic and butyric. The source of inoculum was not consistent in the changes observed on in vitro fermentation evaluated with different copper levels. Levels between 5 and 10 ppm of copper are suggested to produce metabolic improvements in rumen fermentation.

Master thesis

Biogás Cobre Inóculos Ovino Caprino Bovino Biogas Copper Inoculants Sheep Goats Cattle Ganadería Maestría CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Nanocompuestos de polipropileno con nanopartículas de cobre: preparación, activación superficial por plasma y actividad antibacteriana

Nanocomposites based on Polypropylene and Copper Nanoparticles: Preparation, Surface Activation by Plasma and Antibacterial Activity

Beatriz Liliana España Sánchez Jose Alberto Rodriguez González Pablo González Morones MARIA GUADALUPE NEIRA VELAZQUEZ BERNARDO FRANCO BARCENAS (2014)

El presente trabajo reporta la preparación de nanocompuestos de polipropileno con nanopartículas de cobre (PP/nCu) a partir de mezclado en fundido, así como su tratamiento superficial mediante plasma de argón, con el fin de incrementar la actividad antibacteriana de los compuestos obtenidos. El análisis superficial del nanocompuesto corroborado mediante microscopía electrónica de barrido (SEM) y la microscopía de fuerza atómica (AFM) demostraron que el tratamiento con plasma de argón modifica la superficie del compuesto, incrementando la exposición de las nanopartículas y, por lo tanto, la rugosidad del material. Se encontró mediante estudios de espectroscopia fotoelectrónica de rayos X (XPS) y ángulo de contacto que el plasma de argón, favorece la ruptura de cadenas poliméricas en la superficie, removiendo cadenas poliméricas y formando estudios de sitios activos que al contacto con el medio ambiente insertan especies de oxígeno y nitrógeno, incrementando la polaridad de la materia. La exposición superficial de nanopartículas y el cambio en la polaridad de los nanocompuestos erosionados produjo un incremento significativo en la actividad antimicrobiana contra las bacterias patógenas Staphylococcus aureus y Pseudomonas aeruginosa. El uso de plasma para la modificación superficial de nanocompuestos resulta una herramienta eficaz para la obtención de nanomateriales antimicrobianos de alto valor agregado

This work reports the preparation of polypropylene nanocomposites with copper nanoparticles (PP/nCu) by melt blending, as well as their surface treatment by argon plasma in order to increase the antibacterial activity of compounds obtained. The nanocomposite surface analysis, corroborated by means of Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), demonstrates that argon plasma treatment modifies the surface of the compound, increasing the exposure of nanoparticles and, therefore, roughness of the material. Argon plasma favors polymeric chain scission at the surface, removing polymer chains and forming active sites, which in contact with the environment incorporates oxygen and nitrogen species, increasing the material ́s polarity, as demonstrated by X-ray photoelectron spectroscopy (XPS) analysis and contact angle measurements. The exposure of surface nanoparticles and polarity shifts of eroded nanocomposites produced a significant increase in antimicrobial activity against pathogenic bacteria Staphylococcus aureus and Pseudomonas aeruginosa. Plasma treatment use for surface modification of nanocomposites is an ef-fective tool to obtain antimicrobial nanomaterials with a high value-added

Article

MEDICINA Y CIENCIAS DE LA SALUD Nanocompuestos Cobre Plasma Antibacteriano Nanocomposites Copper Plasma Antibacterial

Copper stress on photosynthesis of Black Mangle (Avicennia germinans)

DANIEL GONZALEZ MENDOZA FRANCISCO LEONEL ESPADAS Y GIL LUIS FERNANDO ESCOBOZA GARCIA JORGE MANUEL SANTAMARIA FERNANDEZ JOSE OMAR ZAPATA PEREZ (2013)

The effects of copper toxicity on the photosynthetic activities of Avicennia germinans was investigated using two CuSO4 concentrations (0.062 and 0.33 M) added in Hoagland's solution in an aerated hydroponic system. Photosynthesis and chlorophyll fluorescence were measured after 30 h of copper stress. Results obtained in this study show that increasing levels of Cu+2 of 0.062 and 0.33 M Cu+2 resulted in a general reduction of the stomatal conductance (28 and 18%, respectively) and 100% of inhibition of net photosynthesis. Additionally, at these concentrations of Cu+2, reductions of chlorophyll fluorescence parameters were also observed. These changes suggested that the photosynthetic apparatus of Avicennia germinans was the primary target of the Cu+2 action. It is concluded that Cu+2 ions causes a drastic decline in photosynthetic gas exchange and Chlorophyll fluorescence parameters in A. germinans leaves.

Article

AVICENNIA GERMINANS CHLOROPHYLL FL UORESCENCE COPPER PHOTOSYSTEM II PHOTOSYNTHESIS BIOLOGÍA Y QUÍMICA

Concentración óptima y tóxica de cobre para el crecimiento de bacterias ruminales

DANIEL CERVANTES GOMEZ (2012)

Tesis (Maestría en Ciencias, especialista en Ganadería).- Colegio de Postgraduados, 2012.

El cobre (Cu) es un micromineral que cumple funciones esenciales en el organismo de los animales; del mismo modo es necesario para las bacterias ruminales, implicando que todos los nutrientes que requieren los microrganismos, dentro de estos el cobre, deben estar disponibles en el rumen en forma estable y continúa para asegurar su crecimiento. Por lo anterior, en el presente estudio se desarrollaron dos ensayos experimentales para determinar la concentración óptima y tóxica de cobre, con base al crecimiento y la actividad de las bacterias ruminales; en el primer experimento se utilizaron seis concentraciones de cobre (0, 10, 20, 30, 40 y 50 ppm), en un medio de cultivo que contenía heno de alfalfa. Los resultados de este ensayo mostraron que las concentraciones de cobre evaluadas no afectaron (p>0.05) el pH y la producción de AGV; sin embargo, la población de bacterias totales disminuyó (p<0.05) con el aporte de 40 ppm de Cu a las 72 h de incubación. Estos resultados, no permitieron evidenciar con claridad cual es la cantidad óptima y tóxica de cobre en el crecimiento bacteriano. El segundo experimento se incrementaron las concentraciones de cobre: Testigo 0, tratamientos de 20, 40, 60, 80 y 100 ppm. Hubo una disminución (p<0.05) de 20 y 55 % en la población total de bacterias, de 23.5 y 23 % en la digestibilidad in vitro de MO, y de 29 y 37 % en la producción total de AGV, con cantidades de 80 y 100 ppm de cobre. Los resultados obtenidos en este trabajo sugieren que la cantidad óptima de Cu para las bacterias ruminales se encuentra entre 40 a 60 ppm, y la concentración tóxica es de 80 ppm o más. _______________ OPTIMAL AND TOXIC COPPER CONCENTRATION FOR RUMINAL BACTERIAL GROWTH. ABSTRACT: Copper (Cu) is an essential mineral that support animal body functions, in the same way, is essential for rumen bacteria growth, implying that all the minerals needed by microbes, including copper, should be available at the rumen in a stable and continues concentration to ensure its growth. Therefore, in the present study, two assays were developed to determine the optimal and toxic copper level, based on ruminal bacterial growth and their activity; in the first trial six copper levels (0, 10, 20, 30, 40 and 50 ppm) were evaluated, using a culture medium containing alfalfa hay. Copper treatments didn’t affect (p>0.05) pH and VFA production in the first trial; however, total bacterial population decrease (p<0.05) at 72 h of incubation, when the culture medium contain 40 ppm Cu; but these preliminary results didn’t explain clearly the optimal and toxic copper level on bacterial growth. Therefore in the second assay, copper levels were increased from 0, 20, 40, 60, 80, to 100 ppm, make evident a decrease (p<0.05) of 20 and 55 %, 23.5 and 23 %, 29 and 37 % on total bacterial population, OM in vitro digestibility, and VFA total production, with 80 and 100 ppm Cu, respectively. These results suggest that optimum cupper level for rumen bacterial growth is observed between 40 to 60 ppm, and the toxic concentration occurs at 80 ppm or higher.

Master thesis

Cobre Concentración óptima y tóxica Bacterias ruminales Digestibilidad in vitro Copper Optimal and toxic concentration Ruminal microbes In vitro digestibility Ganadería Maestría CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Surface modification of TiO2 with Ag nanoparticles and CuO nanoclusters for application in photocatalysis

María Guadalupe Méndez Medrano Ewa Kowalska Anaïs Lehoux Alexandre Hérissan Bunsho Ohtani DANIEL BAHENA URIBE Valérie Briois Christophe Colbeau Justin JOSE LUIS RODRIGUEZ LOPEZ Hynd Remita (2016)

"Ag and CuO nanoparticles (NPs) synthesized on the surface of commercial TiO2 (P25) by radiolytic reduction were characterized by diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). In the case of modification with silver and copper, results from HAADF-STEM, EDS, XPS, and XAS show that Ag@CuO nanoparticles (large silver cores decorated with small clusters of CuO) were obtained on TiO2-P25. The photocatalytic properties of bare and modified TiO2-P25 were studied for phenol photodegradation and for acetic acid oxidation under UV and visible irradiation. The mechanisms involved in photo catalysis were studied by time-resolved microwave conductivity (TRMC) and action spectra (AS). The electronic properties of the surface-modified TiO2-P25 were studied by TRMC to follow the charge-carrier dynamics. The modification with Ag nanoparticles or CuO nanoclusters induces an increase in the photocatalytic activity under both IN and visible light. The photocatalytic activity of Ag@CuO/P25 is higher under-UV light but lower under visible light compared to the activity of CuO/P25 and Ag/P25. TRMC measurements show that surface modification of TiO2-P25 with Ag, CuO, and Ag@CuO nanoparticles plays a role in charge-carrier separation, increasing the activity under UV-light, and that Ag@CuO NPs are more efficient electron scavengers than Ag NPs and CuO nanoclusters. The localized surface plasmon resonance (LSPR) of Ag NPs and the narrow band gap of CuO induce an activity under visible light. The TRMC shows also responses under visible-light irradiation at different fixed wavelengths indicating that electrons are injected from Ag NPs in the conduction band (CB) of TiO2-P25. Moreover, under visible light, the photocatalytic activity of CuO/P25 is higher than that of plasmonic Ag/P25. CuO is able to activate TiO2-P25 in a wider range of wavelengths under visible-light irradiation, compared to the activation achieved by the presence of silver. The action spectra correlate with the-absorption spectra for irradiation wavelengths in the range of 350-470 nm proving that dem-xi-position of acetic acid is carried out by a photocatalytic mechanism."

Article

Charger-carrier lifetimes Gold-silver alloy Titanium-dioxide Photoelectron-spectroscopy Copper Degradation Oxidation Ions Segregation Excitation BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA

Bone copper content in sheep in relation to their drinking water source

ARTURO FRANCISCO CASTELLANOS RUELAS (2017)

The aim was to estimate the Cu content in the bones of grazing sheep and relate it to their drinking water. Cu was analyzed by taking bone biopsies. Samples from the twelfth rib were taken in 107 animals and water samples were collected from forty wells in the same farms located in four agroecological areas in Yucatán state, Mexico. Cu was analyzed by atomic absorption. Data were analyzed using the least squares method. Cu content in bone tissue was: weaned 0.66 a; Females prior to rst gestation 0.57 b and ewes 0.64 a mg/kg-1. Normal content in bone is 2-3 mg/kg-1, indicating a de ciency in the animals. Cu in water was 0.15 ab, 0.12 b, 0.16 ab and 0.19 a mg/L-1 in the center, east, west and south part of the State respectively. Cu concentration in water for animal consumption was low. In conclusion, Cu de ciency was diagnosed in grazing sheep that could be associated with the low Cu content in the drinking water.

Article

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA copper bone biopsy grazing