RESUMO
In this work, the assessment of Azadirachta indica, Tagetes erecta, Chrysanthemum morifolium, and Lentinula edodes extracts as catalysts for the green synthesis of zinc oxide nanoparticles (ZnO NPs) was performed. The photocatalytic properties of ZnO NPs were investigated by the photodegradation of methylene blue (MB) dye under sunlight irradiation. UV-visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Thermogravimetric (TGA), and Brunauer-Emmett-Teller analysis (BET) were used for the characterization of samples. The XRD results indicate that all synthesized nanoparticles have a hexagonal wurtzite crystalline structure, which was confirmed by TEM. Further, TEM analysis proved the formation of spherical and hemispherical nanoparticles of ZnO with a size in the range of 14-32 nm, which were found in aggregate shape; such a size was well below the size of the particles synthesized with no extract (~43 nm). ZnO NPs produced with Tagetes erecta and Lentinula edodes showed the best photocatalytic activity, matching with the maximum adsorbed MB molecules (45.41 and 58.73%, respectively). MB was completely degraded in 45 min using Tagetes erecta and 120 min using Lentinula edodes when subjected to solar irradiation.
Assuntos
Nanopartículas Metálicas/química , Extratos Vegetais/química , Tagetes/química , Acetato de Zinco/química , Óxido de Zinco/química , Catálise , Química Verde , Azul de Metileno/química , Fotólise , Folhas de Planta/química , Luz Solar , Poluição Química da ÁguaRESUMO
ZnO samples were prepared by sol-gel method applying a factorial design in order to improve the photocatalytic properties of the semiconductor oxide in the NO photooxidation reaction. The concentrations of zinc acetate and ammonium hydroxide were selected as critical variables in the synthesis of ZnO. Nine samples of ZnO were obtained as product of the factorial design and were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, and N2 adsorption-desorption isotherms. The photocatalytic activity of ZnO samples was associated with the physical properties developed by each sample according to its respective conditions of synthesis. Some photocatalytic reaction parameters, such as mass of photocatalyst, irradiance, and relative humidity, were modified in order to evaluate its effect in the photocatalytic conversion of NO. As a relevant point, the relative humidity played an important role in the increase of the selectivity of the NO photooxidation reaction to innocuous nitrate ions when ZnO was used as photocatalyst.
Assuntos
Poluentes Ambientais/química , Óxido Nítrico/química , Processos Fotoquímicos , Óxido de Zinco/química , Óxido de Zinco/síntese química , Adsorção , Hidróxido de Amônia/química , Catálise , Poluentes Ambientais/isolamento & purificação , Óxido Nítrico/isolamento & purificação , Oxirredução , Acetato de Zinco/químicaRESUMO
BACKGROUND: We have evidence for enterohepatic cycling of bilirubin experimentally and in vivo in humans. This study was designed to investigate whether Zn salts might inhibit such cycling of bilirubin. MATERIALS AND METHODS: Micellar bile salt solutions with unconjugated bilirubin were prepared, appropriate concentrations of Zn salts were added, and unconjugated bilirubin precipitation was measured. Hamsters and Wistar rats were fed a chow diet or a chow diet enriched with 1% ZnSO4, and bilirubin secretion rates were monitored. RESULTS: Unconjugated bilirubin was precipitated maximally (90%) after a 10-min incubation with 5 mM Zn salts in the pH range of 6.8-9.0. In control hamsters, total bilirubin secretion rates into bile were 36.0 +/- 2.8 nmol h(-1) 100g(-1) body weight, whereas they were 25.0 +/- 3.3 nmol h-1 100(-1) g in the ZnSO4 group (P < 0.05). CONCLUSIONS: Zn salts that flocculate at physiological pH adsorb unconjugated bilirubin almost completely from unsaturated micellar BS solutions. In addition, Zn salts administered orally suppress biliary bilirubin secretion rates in hamsters. These findings suggest that the administration of Zn salts may inhibit the enterohepatic cycling of unconjugated bilirubin in humans who are predisposed to pigment gallstone formation due to diet, disease or drugs.
Assuntos
Bilirrubina/metabolismo , Fígado/metabolismo , Sulfato de Zinco/farmacocinética , Animais , Ácidos e Sais Biliares/química , Ácidos e Sais Biliares/farmacologia , Fístula Biliar/metabolismo , Bilirrubina/química , Carbonatos/química , Carbonatos/farmacologia , Precipitação Química , Colelitíase/metabolismo , Cricetinae , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Masculino , Mesocricetus , Ratos , Ratos Wistar , Acetato de Zinco/química , Acetato de Zinco/farmacologia , Compostos de Zinco/química , Compostos de Zinco/farmacologia , Sulfato de Zinco/químicaRESUMO
La toma de impresiones al paciente totalmente desdentado tiene como objetivo registrar la anatomía de la cavidad bucal para reproducirla en escayola, y poder confeccionar las prótesis a su medida. Exponemos en este artículo los criterios recomendados para conseguir unas buenas impresiones. Aportamos pequeñas sugerencias que pueden facilitar al profesional la adquisición de la destreza necesaria para obtener unas impresiones correctas
Assuntos
Humanos , Pessoa de Meia-Idade , Materiais para Moldagem Odontológica , Técnica de Moldagem Odontológica , Prótese Total/normas , Alginatos/química , Sulfato de Cálcio/normas , Coloides/química , Modelos Dentários/normas , Arcada Edêntula/reabilitação , Arcada Osseodentária/anatomia & histologia , Silicones/química , Acetato de Zinco/químicaRESUMO
La toma de impresiones al paciente totalmente desdentado tiene como objetivo registrar la anatomía de la cavidad bucal para reproducirla en escayola, y poder confeccionar las prótesis a su medida. Exponemos en este artículo los criterios recomendados para conseguir unas buenas impresiones. Aportamos pequeñas sugerencias que pueden facilitar al profesional la adquisición de la destreza necesaria para obtener unas impresiones correctas (AU)