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Abstract Graphene oxide (GO) is one of the main precursors for the production of graphene and other graphene-based materials. We report a simple, safe, and fast synthesis method to obtain graphene oxide as a functional material for battery-type electrodes. Washing and lyophilization processes were performed to evaluate their effects on exfoliation and removal of functional groups from graphene sheets. Sample GO1 consisted of a 10-layer stack of oxidized graphene, while sample GO2 had 8 stacked layers. The difference between them was an extra washing and lyophilization process in the GO2 sample. The electrochemical performance of graphene oxide-based electrodes, classified as battery-type, indicated an improved specific capacity of 10.15 C.g-1 for GO1 against 4.55 C.g-1 for GO2 at a specific current of 0.5 A.g-1. This superior battery-type behavior of the GO1 electrode, also confirmed by electrochemical impedance spectroscopy, was most likely due to a higher degree of oxygenated groups on its surface, as shown by energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) studies.

https://doi.org/10.1590/0366-69132023693903474

Cepas de Yarrowia lipolytica, aisladas de lagunas altoandinas del Perú contaminadas con relaves mineros, como potenciales agentes para la biorremediación de metales pesados
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Sánchez-Rojas, Tito L.

; Macedo-Prada, Diego

; Ramírez, Pablo S.

; Arrieta, Lee K.

; Durán, Yerson

; Flores, Abad

; Manya, Walter F.

; Guerra, Gregory

Ecología Aplicada

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Ene 2023, Volumen 22 Nº 1 Paginas 1 - 16

Resumen: En Es | Texto: En Es | PDF: En | PDF: Es

Abstract The objective of this work was to study the mean lethal concentration (LC50) and the biosorption capacity of heavy metals in isolated yeasts from Lake Junín and the Yanamate tailings facility. In both bodies of water were evaluated: pH, electrical conductivity, temperature, total dissolved solids (STD) and heavy metals by ICM-MS, according to the Environmental Quality Standards (ECA) of the Ministry of the Environment-MINAM of Peru. The physicochemical parameters evaluated in Lake Junín were higher than the maximum permissible limits (MPL) for the following metals: arsenic, cadmium, copper, chromium and lead. In the Yanamate tailings facility, the evaluated parameters were out of the LMP for type IV water ECAs: pH below 3 (acids), high electrical conductivities and high concentrations of heavy metals. From the sampled waters, yeasts were isolated in YPG medium at 10 ° C and 20 ° C. The LC50 of the Cr+6, Cu+2, Cd+2 and Hg+2 ions in Y. lipolytica AMJ3 were 0.24 mM, 1.34 mM, 0.54 mM y 7.5 0.04 mM in the order described; while the strain Y. lipolytica AMJ6 showed a LC50 of 1.06 mM, 1.42 mM, 0.49 mM y 0.05 mM in the same order. The biosorption capacity of the Cu+2 ion was 90% in the case of the AMJ3 strain, and 92% in the AMJ6 strain, at a concentration of 1.26 mM; likewise, the biosorption of the Cr+6 ion was close to 90% in both strains (AMJ3 and AMJ6) at concentrations of 0.24 mM and 0.96 mM, respectively. Nucleotide sequence analysis of AMJ3 and AMJ6 strains confirmed 100% identity in the Yarrowia lipolytica clade. These LC50 and biosorption capacity results indicate that the studied yeasts have potential in the bioremediation of water bodies and soils contaminated with heavy metals.

Resumen El objetivo del presente trabajo fue estudiar la concentración letal media (CL50) y la capacidad de biosorción de metales pesados en levaduras aisladas del Lago Junín y la relavera Yanamate. Se evaluaron en ambos cuerpos de agua: pH, conductividad eléctrica, temperatura, sólidos totales disueltos (STD) y metales pesados por ICM-MS, según los Estándares de Calidad Ambiental (ECA) del Ministerio del Ambiente-MINAM del Perú. Los parámetros fisicoquímicos evaluados en el Lago Junín fueron superiores a los límites máximos permisibles (LMP) para los siguientes metales: arsénico, cadmio, cobre, cromo y plomo. En la relavera Yanamate, los parámetros evaluados estuvieron fuera del LMP para los ECA de aguas tipo IV: pH inferiores a 3 (ácidos), altas conductividades eléctricas y elevadas concentraciones de metales pesados. A partir de las aguas muestreadas, se aislaron levaduras en medio YPG a 10 °C y 20 °C. La CL50 de los iones Cr+6, Cu+2, Cd+2 y Hg+2 en Y. lipolytica AMJ3 fue 0.24 mM, 1.34 mM, 0.54 mM y 7.5 0.04 mM en el orden descrito; en tanto la cepa Y. lipolytica AMJ6 mostró una CL50 de 1.06 mM, 1.42 mM, 0.49 mM y 0.05 mM en el mismo orden. La capacidad de biosorción del ion Cu+2 fue del 90% en el caso de la cepa AMJ3 y 92% en la cepa AMJ6, a una concentración de 1.26 mM; asimismo, la biosorción del ion Cr+6 fue cercana al 90% en ambas cepas (AMJ3 y AMJ6) a concentraciones de 0.24 mM y 0.96 mM, respectivamente. Los análisis de las secuencias nucleotídicas de las cepas AMJ3 y AMJ6 confirmaron una identidad del 100% en el clado de Yarrowia lipolytica. Los resultados obtenidos de CL50 y la capacidad de biosorción indican que las levaduras bajo estudio tienen potencial en la biorremediación de cuerpos de agua y suelos contaminados con metales pesados.

https://doi.org/10.21704/rea.v22i1.1978

Tailoring the properties of Y2O3 via synthesis parameters varied during the PVA-assisted sol-gel route YO Y O Y2O PVAassisted PVA assisted solgel sol gel
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Carvalho, J. C. C.

; Bispo, G. F. C.

; Lilge, T. S.

; Bezerra, C. S.

; Andrade, A. B.

; Macedo, Z. S.

; Valerio, M. E. G.

Cerâmica

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Ene 2023, Volumen 69 Nº 389 Paginas 48 - 53

Resumen: En | Texto: En | PDF: En

Abstract The effect of synthesis parameters on the microstructural behavior and morphology during the yttrium oxide (Y2O3) formation is reported. Y2O3 crystals were produced by a modified sol-gel route assisted by polyvinyl alcohol solution varying the calcination temperature and solution pH. The crystalline phase formation was investigated using X-ray powder diffraction combined with the Rietveld refinement method. The microstructural properties were analyzed by using the Williamson-Hall formalism. The calcination temperature followed the thermal events observed in the differential thermal analysis combined with the thermogravimetric analysis of the precursor xerogel. It was seen that the combination of PVA and pH variation can be used to minimize the calcination time and temperature. The morphological analysis showed samples with different sizes and appearances depending on pH and calcination temperature. Therefore, it was shown that the parameters in the synthesis process can be used to tailor the properties of Y2O3, such as crystallite size, degree of structural ordering, and morphology, and consequently, improve the desired application. YO Y O (Y2O3 reported Y2O solgel sol gel Xray X ray method WilliamsonHall Williamson Hall formalism xerogel Therefore size ordering consequently application (Y2O

https://doi.org/10.1590/0366-69132023693893425

First of report of occurrence and damage of Synoeca cyanea (Hymenoptera: Vespidae) on Mangifera indica L. in Brazil Hymenoptera (Hymenoptera Vespidae L
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Rocha, E. A. A.

; Silva, L. F.

; Fernandes, M. E. S.

; Macedo, A. F.

; Soares, C. S.

; Pereira, R. C.

; Fernandes, F. L.

Brazilian Journal of Biology

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2023, Volumen 83 elocation e275126

Resumen: En | Texto: En | PDF: En

https://doi.org/10.1590/1519-6984.275126

Octadecanal as the Male-Produced Aggregation Pheromone of the Coconut Weevil, Amerrhinus ynca (Coleoptera: Curculionidae)
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Santos Neta, Palmira L. dos

; Fávaro, Carla F.

; Macedo, Sarah O.

; Moura, José Inácio L.

; Bello, Jan E.

; Santos, Rândilla R. C.

; Zarbin, Paulo H. G.

Journal of the Brazilian Chemical Society

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Oct 2021, Volumen 32 Nº 10 Paginas 2017 - 2021

Resumen: En | Texto: En | PDF: En

The beetle Amerrhinus ynca Sahlberg, 1823 (Coleoptera: Curculionidae) causes damage to several species of the Arecaceae family. The larvae of this palm weevil damage palm trees by causing perforations in the leaf rachis, obstructing the flow of nutrients to the plant. To date, are no registered insecticides for the control of A. ynca. An efficient control strategy would be the use of synthetic pheromones of this beetle for integrated pest management tactics. In this work, the aggregation pheromone of A. ynca was identified from adults collected as larvae and pupae from the rachis of coconut palm. The volatile compounds produced by A. ynca were collected via headspace aeration of adult beetles, and the identification of the pheromone was performed with gas chromatography coupled to mass spectrometry (GC-MS), GC-Fourier transform infrared spectroscopy (GC-FTIR) and GC-electroantenographic detector (GC-EAD). Dual-choice olfactometry experiments were performed to evaluate the bioactivity of the synthetic pheromone. GC analyses showed the presence of a male-specific compound that was identified as octadecanal. In GC-EAD analyses, synthetic octadecanal elicited responses of A. ynca female antennae. Behavioral bioassays showed attractiveness of synthetic compound for males and females, indicating octadecanal as the aggregation pheromone of A. ynca.

https://doi.org/10.21577/0103-5053.20210087 52 descargas

Priority conservation of medicinal woody plants from protected forests based on ecological and ethnobotanical data
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OLIVEIRA, SAMARA F.

; RANGEL, JULIANA M.L.

; MACEDO, JULIMERY G.F.

; SILVA, SAMILLE L.

; RIBEIRO, DAIANY A.

; MACEDO, MARIA SORAYA

; SEIXAS, EMÍDIA NAIANA C.

; MACÊDO, DELMACIA G.

; SARAIVA, MANUELE E.

; LINHARES, KARINA V.

; MENDONÇA, ANA CLEIDE A.M.

; SOUZA, MARTA MARIA A.

; ARAÚJO, ELCIDA L.

; SILVA, MARIA ARLENE P.

Anais da Academia Brasileira de Ciências

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2021, Volumen 93 elocation e20201769

Resumen: En | Texto: En | PDF: En

Abstract The combination of ethnobotanical and ecological knowledge is an important tool in indicating priority species for conservation. We sought to gather ethnobotanical knowledge on the diversity and use of woody medicinal plants in the Chapada Araripe region, assessing the real availability of woody medicinal resources in the Araripe Forests in the cerrado and carrasco areas, and indicate priority species for conservation. A total of 107 species were recorded in the ethnobotanical surveys, classified into 39 families and 83 genera, of which 92 species, 36 families and 70 genera for the cerrado areas, and 47 species, 25 families and 39 genera, for the carrasco areas. 59% were present in the phytosociological surveys for cerrado and 38% for carrascos. Species with high versatility of medicinal use did not necessarily have high local availability, and some were not recorded in the sampling. Thirteen species in cerrados and four in carrascos were indicated as conservation priorities. Use not aligned of species with the reality of the present time can indeed affect the vegetation landscape, and in a future scenario, not taking local measures to conserve protected forest resources, besides increasing the lists of local conservation priorities, can affect economic practices, increasing social and environmental conflicts.

https://doi.org/10.1590/0001-3765202120201769 36 descargas

Variabilidad en las densidades, las velocidades del ultrasonido y los módulos dinámicos en tres maderas mexicanas y tres maderas japonesas
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Sotomayor Castellanos, Javier Ramón

; Macedo Alquicira, Isarael

; Chávez García, Hugo Luis

Ingeniería y Desarrollo

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Dic 2020, Volumen 38 Nº 2 Paginas 382 - 399

Resumen: Es En | Texto: Es En | PDF: Es | PDF: En

Resumen La variabilidad en los valores experimentales de la densidad, la velocidad del ultrasonido y el módulo dinámico puede estar asociada al efecto de las propiedades intrínsecas de la madera y ser diferente entre especies y sus direcciones de anisotropía. Para verificar esta hipótesis, el objetivo de la investigación fue determinar estos parámetros en tres maderas mexica nas: Pinus pseudostrobus, Tabebuia rosea y Quercus spp., y en tres maderas japonesas: Paulownia tomentosa, Cryptomeria japonica y Fagus crenata. Se realizaron pruebas de ultrasonido en las direcciones radial, tangencial y longitudinal; igualmente, se determinaron las relaciones de anisotropía y las longitudes de onda. Los valores de las densidades, las velocidades del ultrasonido y los módulos dinámicos para las maderas de P. pseudostrobus, T. rosea, Quercus spp., P. tomentosa, C. japonica y F. crenata presentan una amplia diversidad entre especies y en una especie. Esta variabilidad se puede caracterizar con los coeficientes de variación y de determinación. Las pruebas de ultrasonido son útiles para confirmar el carácter anisotrópico de la velocidad del ultrasonido y del módulo de elasticidad de la madera. Para esto, es suficiente un tamaño de muestra de 35 probetas orientadas en las direcciones radial, tangencial y longitudinal.

Abstract The variability in the experimental values of the density, the speed of ultrasound, and the dynamic modulus may be associated with the effect of the intrinsic properties of wood, and they are different between species and their directions of anisotropy. To verify this hypothesis, the objective of the investigation was to determine these parameters in three Mexican woods: Pinus pseudostrobus, Tabebuia rosea, and Quercus spp; and from three Japanese woods: Paulownia tomentosa, Cryptomeria japonica, and Fagus crenata. Ultrasound tests were perfor med in the radial, tangential, and longitudinal directions, and the anisotropy relationships and wavelengths were determined. The values of the densities, the speeds of ultrasound, and the dynamic modules for the woods of P. pseudos trobus, T. rosea, Quercus spp, P. tomentosa, C. japonica, and F. crenata present a wide and diverse range, both inter- and intra-species. This variability can be characterized with the coefficients of variation and determination. Ultrasound tests are useful for confirming the anisotropic character of ultrasound speed and modulus of elasticity of wood. For this, a sample size of 35 specimens oriented in the radial, tangential, and longitudinal directions is sufficient.

https://doi.org/10.14482/inde.38.2.624.15 24 descargas

Application of beta zeolite in allylation reaction aiming formation of new C-C bonds
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Macedo, V. K. S. A.

; Santos, C. S.

; Mello, M. I. S. de

; Alves, J. A. B. L. R.

; Barros, J. M. F.

; Freitas, J. C. R.

Cerâmica

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Sep 2020, Volumen 66 Nº 379 Paginas 243 - 249

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

Resumo Este estudo descreve a formação de novas ligações C-C através da reação de alilação de diferentes aldeídos promovida pela zeólita beta. Este método ecologicamente amigável foi caracterizado por sua eficiência, versatilidade e quimiosseletividade, na formação de diferentes álcoois homoalílicos. Os álcoois homoalílicos foram obtidos em bons rendimentos (80% a 96%), tempos reacionais curtos (30 a 75 min) em temperatura ambiente e sem a necessidade de purificações adicionais. Além disso, foi utilizada água como cossolvente garantindo ao método um desenvolvimento no âmbito da química verde. Adicionalmente, constatou-se que a zeólita beta pode ser reutilizada por até um ciclo reacional sem perda de sua eficiência.

Abstract This study describes the formation of new C-C bonds through the allylation reaction of different aldehydes promoted by beta zeolite. This environmentally friendly method was characterized by its efficiency, versatility, and chemoselectivity in the formation of different homoallylic alcohols. Homoallylic alcohols were obtained in good yields (80% to 96%), short reaction times (30 to 75 min) at room temperature, and without the need for additional purifications. In addition, water was used as a co-solvent, ensuring the method a development in the field of green chemistry. Moreover, it was found that the zeolite beta can be reused for up to one reaction cycle without loss of its efficiency.

https://doi.org/10.1590/0366-69132020663792553 673 descargas

Improving nutrient availability of defatted rice bran using different phytase sources applied to grass carp (Ctenopharyngodon idella) diet
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RIES, EDI F.

; FERREIRA, CRISTIANO C.

; GOULART, FERNANDA R.

; LOVATTO, NAGLEZI M.

; LOUREIRO, BRUNO B.

; BENDER, ANA B.B.

; MACEDO, GABRIELA A.

; SILVA, LEILA P. DA

Anais da Academia Brasileira de Ciências

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2020, Volumen 92 Nº 3 elocation e20190201

Resumen: En | Texto: En | PDF: En

Abstract In the present study, we evaluated the effects of the hydrolysis of phytate of defatted rice bran (DRB) by a pretreatment with non-commercial phytase produced by Saccharomyces cerevisiae (DRB-PS) compared to the application of Natuphos® (commercial phytase produced by the BASF Company) (DRB-PN) in diets for grass carp, Ctenopharyngodon idella. Fish (57.55 ± 0.4 g) fed one of the experimental diets in triplicates for 35 days. Effects of the phytase used on blood parameters, intestinal proteases and hepatic glucose were not observed (p > 0.05). Similarly, no differences were found for serum phosphorus (P). However, were found higher levels of calcium (9 and 5.25%) in the control treatment in relation to DRB-PS and DRB-PN respectively, besides higher calcium-phosphorus ratio was found in this treatment. For the fish carcass composition was not statistically different (p > 0.05) except total lipids, which showed its highest content in fish fed on the DRB-PN diet (p < 0.05). The obtained results suggested that the use of the phytase, irrespective to its source may eliminate the use of traditional P sources in fish diets.

https://doi.org/10.1590/0001-3765202020190201 615 descargas

10.

Alterações fisiológicas e bioquímicas de sementes de Acacia mangiumWilld. durante o armazenamento
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Pádua, Guilherme V. G. de

; Oliveira, Danilo F. A. de

; Félix, Francival Cardoso

; Macedo, Cristiane E. C. de

; Voigt, Eduardo L.

; Ferrari, Cibele S.

; Pacheco, Mauro V.

Revista de Ciências Agrárias

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Dic 2019, Volumen 42 Nº 4 Paginas 141 - 150

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

As sementes estão continuamente expostas ao processo de deterioração, o qual envolve alterações fisiológicas, bioquímicas, físicas e citológicas. Assim, este estudo teve por objetivo avaliar alterações fisiológicas e bioquímicas em sementes de Acacia mangium durante o armazenamento em três ambientes. Para este fim, as sementes foram armazenadas em sacos de polietileno semipermeáveis durante os períodos de 0, 3, 6, 9, 12 e 15 meses em três condições de armazenamento: congelador (T = -20 ± 3 ºC; U.R. = 49 ± 15%), frigorífico doméstico (T = 6 ± 3 ºC; U.R. = 55 ± 14%) e sala climatizada (T = 27 ± 4 ºC; U.R. = 56 ± 13%). Foram realizadas as seguintes determinações e testes: teor de água, germinação, primeira contagem de germinação, índice de velocidade de germinação, massa seca de plântulas, emergência, índice de velocidade de emergência, açúcares solúveis totais, açúcares não redutores, aminoácidos livres totais, amido e proteínas solúveis. As sementes de A. mangium conservam a qualidade fisiológica durante 12 meses quando armazenadas quer em congelador, frigorífico doméstico ou sala climatizada. Não foi possível verificar um padrão de alteração no conteúdo de amido, açúcares solúveis totais e açúcares não redutores.

Seeds are continually exposed to the deterioration process, which involves physiological, biochemical, physical and cytological changes. Thus, the objective of this study was to evaluate physiological and biochemical changes in Acacia mangium seeds during storage in three environments. For this purpose, the seeds were stored in semi-permeable polyethylene bags during periods of 0, 3, 6, 9, 12 and 15 months under three conditions: frezer (T = -20 ± 3 ºC, RH = 49 ± 15%), refrigerator (T = 6 ± 3 °C, RH = 55 ± 14%) and air-conditioned room (T = 27 ± 4 °C, RH = 56 ± 13%). The following determinations and tests were performed: water content, germination, first germination count, germination speed index, seedling dry mass, emergence rate, emergence speed index, total soluble sugars, non-reducing sugars, total free amino acids, starch and soluble proteins. The seeds of A. mangium retain the physiological quality for 12 months when stored in a frezer, domestic refrigerator and heated room. It was not possible to verify a pattern of change in the content of starch, total soluble sugars and non-reducing sugars.

https://doi.org/10.19084/rca.17552 296 descargas

11.

Brazilian stingless bee propolis and geopropolis: promising sources of biologically active compounds
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Lavinas, Flavia C.

; Macedo, Ellis Helena B.C.

; Sá, Gabriel B.L.

; Amaral, Ana Claudia F.

; Silva, Jefferson R.A.

; Azevedo, Mariana M.B.

; Vieira, Bárbara A.

; Domingos, Thaisa Francielle S.

; Vermelho, Alane B.

; Carneiro, Carla S.

; Rodrigues, Igor A.

Revista Brasileira de Farmacognosia

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Jun 2019, Volumen 29 Nº 3 Paginas 389 - 399

Resumen: En | Texto: En | PDF: En

ABSTRACT Stingless bee products such as honey, pollen, propolis, and geopropolis have been used for centuries in traditional medicine for the treatment of several illnesses. Investigation of the biological activity of stingless bee products, especially propolis and geopropolis, has revealed promising therapeutic properties. About 20% of total Neotropical stingless bees can be found in Brazil. Despite the species diversity, studies on their biological activity are scarce. The present review focuses on the antioxidant and antimicrobial activities of propolis and geopropolis from Brazilian stingless bees. In addition, the toxicity of these natural products was addressed. In order to provide new evidences for the toxic potential of propolis and geopropolis components, an in silico analysis was performed using the ADMET PredictorTM software. We observed that most of studies evaluated only crude ethanol extracts of a limited number of stingless bees species. Propolis and geopropolis displayed antioxidant capacity and antimicrobial activity. Concerning the toxic potential, the extracts of stingless bees propolis and geopropolis were considered safe. Nonetheless, in vitro and in vivo toxicological studies are still necessary.

https://doi.org/10.1016/j.bjp.2018.11.007 1704 descargas

12.

1º Posicionamento Brasileiro sobre o Impacto dos Distúrbios de Sono nas Doenças Cardiovasculares da Sociedade Brasileira de Cardiologia
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Drager, Luciano F.

; Lorenzi-Filho, Geraldo

; Cintra, Fatima Dumas

; Pedrosa, Rodrigo P.

; Bittencourt, Lia R. A.

; Poyares, Dalva

; Carvalho, Carolina Gonzaga

; Moura, Sonia Maria Guimarães Pereira Togeiro

; Santos-Silva, Rogerio

; Bruin, Pedro F. C. de

; Geovanini, Glaucylara R.

; Albuquerque, Felipe N.

; Oliveira, Wercules Antonio Alves de

; Moreira, Gustavo A.

; Ueno, Linda Massako

; Nerbass, Flávia Baggio

; Rondon, Maria Urbana Pinto Brandão

; Barbosa, Eline Rozária Ferreira

; Bertolami, Adriana

; Paola, Angelo Amato Vincenzo de

; Marques, Betânia Braga Silva

; Rizzi, Camila Futado

; Negrão, Carlos Eduardo

; Uchôa, Carlos Henrique Gomes

; Maki-Nunes, Cristiane

; Martinez, Denis

; Fernández, Edmundo Arteaga

; Maroja, Fabrizio U.

; Almeida, Fernanda R.

; Trombetta, Ivani C.

; Storti, Luciana J.

; Bortolotto, Luiz Aparecido

; Mello, Marco Túlio de

; Borges, Melania Aparecida

; Andersen, Monica Levy

; Portilho, Natanael de Paula

; Macedo, Paula

; Alves, Rosana

; Tufik, Sergio

; Fagondes, Simone C.

; Risso, Thaís Telles

Arquivos Brasileiros de Cardiologia

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Ago 2018, Volumen 111 Nº 2 Paginas 290 - 340

Resumen: Pt | Texto: Pt | PDF: Pt

https://doi.org/10.5935/abc.20180154 8719 descargas

13.

Two Novel Donepezil-Lipoic Acid Hybrids: Synthesis, Anticholinesterase and Antioxidant Activities and Theoretical Studies
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Terra, Bruna S.

; Silva, Pedro H. C. da

; Tramarin, Anna

; Franco, Lucas L.

; Cunha, Elaine F. F. da

; Macedo Junior, Fernando

; Ramalho, Teodorico C.

; Bartolini, Manuela

; Bolognesi, Maria L.

; Fátima, Ângelo de

Journal of the Brazilian Chemical Society

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Abr 2018, Volumen 29 Nº 4 Paginas 738 - 747

Resumen: En | Texto: En | PDF: En

Alzheimer disease (AD) is a complex disease related to multiple pathogenic mechanisms. A strategy to develop effective drugs is based on the so-called multi-target directed ligands (MTDL) by using hybrid compounds. So, in the present study, we have designed and synthesized two hybrids, containing the indanone-piperidine moiety of donepezil, a drug approved for the treatment of AD, and the lipoic acid scaffold, an antioxidant compound endowed with neuroprotective effects. One hybrid was synthesized in four steps with 42% global yield, and the other hybrid in six steps with 19% global yield. The latter hybrid displayed moderate inhibitory activity against human acetylcholinesterase (hAChE) and greater activity against human butyrylcholinesterases (hBuChE). The selectivity for hBuChE was further rationalized by theoretical study. Importantly, the second hybrid showed a good antioxidant activity, exhibiting better ability in scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals than lipoic acid.

https://doi.org/10.21577/0103-5053.20170196 1126 descargas

14.

Efeitos da dopagem com gadolínia na densificação e nas propriedades elétricas de soluções sólidas Ce0,99-xGdxCu0,01O2-δ
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Silva, T. H. S.

; Lima, C. G. M.

; Dutra, R. P. S.

; Aquino, F. de M.

; Grilo, J. P. F.

; Rajesh, S.

; Macedo, D. A.

Cerâmica

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Dic 2017, Volumen 63 Nº 368 Paginas 470 - 477

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

Resumo Soluções sólidas à base de céria (CeO2) são materiais promissores para aplicação como eletrólitos de células a combustível de óxido sólido. Apesar das boas propriedades elétricas, um dos principais inconvenientes destes materiais são as altas temperaturas de sinterização (normalmente acima de 1400 °C) necessárias para completa densificação. Com o intuito de melhorar a sinterabilidade da céria, óxidos de metais de transição com baixo ponto de fusão têm sido usados como aditivos de sinterização. Neste contexto, o objetivo deste trabalho foi avaliar o efeito do teor de gadolínia (Gd2O3) na densificação e propriedades elétricas de soluções sólidas de céria com CuO como aditivo de sinterização. Pós com composições nominais Ce0,99-xGdxCu0,01O2-δ (x= 0, 0,2 e 0,3) foram sintetizados pelo método dos precursores poliméricos, calcinados a 500 °C e caracterizados por difratometria de raios X (DRX). A densidade relativa foi avaliada em amostras sinterizadas entre 950 e 1050 °C. As propriedades elétricas foram estudadas por espectroscopia de impedância. Os resultados de DRX indicaram a obtenção de soluções sólidas com estrutura cúbica do tipo fluorita. O uso de materiais nanoparticulados associado a um aditivo de sinterização permitiu a obtenção de cerâmicas com densidades relativas superiores a 92% após sinterização em temperaturas tão baixas quanto 1000 °C. A condutividade elétrica total foi otimizada em amostras com 20% em mol de Gd2O3.

Abstract Ceria (CeO2) based solid solutions are promising materials for use as solid oxide fuel cells electrolytes. Despite good electrical properties, one of the major drawbacks of these materials are the high sintering temperatures (typically above 1400 °C) required for full densification. In order to improve the ceria sinterability, transition metal oxides with low melting point have been used as sintering aid. In this context, the aim of this study was to evaluate the effect of gadolinia (Gd2O3) content on densification and electrical properties of ceria solid solutions with CuO as a sintering aid. Powders with nominal compositions Ce0.99-xGdxCu0.01O2-δ (x= 0, 0.2 and 0.3) were synthesized by the polymeric precursor method, calcined at 500 °C and characterized by X-ray diffraction (XRD). The relative density was evaluated in samples sintered between 950 and 1050 °C. The electrical properties were evaluated by impedance spectroscopy. The XRD results indicated the attainment of solid solutions with cubic fluorite type structure. The use of nanoparticle materials associated with a sintering aid allowed to obtain ceramics with relative densities higher than 92% after sintering at temperatures as low as 1000 °C. The total electrical conductivity was enhanced in samples with 20 mol% Gd2O3.

https://doi.org/10.1590/0366-69132017633682141 703 descargas

15.

Pretreatments and enzymatic hydrolysis of sugarcane bagasse aiming at the enhancement of the yield of glucose and xylose
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Guilherme, A. de A.

; Dantas, P. V. F.

; Soares, J. C. J.

; Santos, E. S. dos

; Fernandes, F. A. N.

; Macedo, G. R. de

Brazilian Journal of Chemical Engineering

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Oct 2017, Volumen 34 Nº 4 Paginas 937 - 947

Resumen: En | Texto: En | PDF: En

ABSTRACT This work studied the enzymatic hydrolysis of sugarcane bagasse aiming at the production of glucose and xylose. The bagasse was subjected to two different pretreatments: combined acid and alkalinepretreatment and hydrogen peroxidepretreatment. The enzymatic hydrolysis was optimized and a kinetic study was carried out in a stirred tank reactor (STR) in batch mode. Optimal conditions were obtained by subjecting the bagasse to the hydrogen peroxide pretreatment followed by enzymatic hydrolysis. The addition of xylanases to the enzymatic mixture improved the production of fermentable sugars by 48%.

https://doi.org/10.1590/0104-6632.20170344s20160225 5045 descargas

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