Thermal and photochemical stability of poly(vinyl alcohol)/modified lignin blends

A kraft lignin derivative (KLD) obtained by reaction with p-aminobenzoic acid/phthalic anhydride was blended with poly(vinyl alcohol) (PVA) by solution casting from DMSO. PVA and PVA/KLD films were exposed to ultraviolet radiation (24, 48, and 96 h) and analyzed by thermogravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (H-1 NMR) spectroscopy, and scanning electron microscopy (SEM). PVA films show a loss of thermal stability due to irradiation. PVA/KLD reveals greater thermal stability than PVA and an increase in thermal stability after irradiation. These results suggest that the incorporation of KLD into PVA provides a gain in thermal and photochemical stability. FTIR, H-1 NMR, DSC, and TG results obtained for the blends suggest that intermolecular interactions between PVA and KLD chains are present. SEM micrographs revealed blend miscibility for a KLD blend content of up to 15 wt%, as observed at magnification of 1000 times. (c) 2005 Elsevier Ltd. All rights reserved.

Enhanced luminescence of Tb3+/Eu3+ doped tellurium oxide glass containing silver nanostructures

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Photoelectrocatalytic degradation of Remazol Brilliant Orange 3R on titanium dioxide thin-film electrodes

Degradation of reactive dye Remazol Brilliant Orange 3R (RBO) has been performed using photoeletrocatalysis. A biased potential is applied across a titanium dioxide thin-film photoelectrode illuminated by UV light. It is suggested that charges photogenerated at the electrode surface give rise to chlorine generation and powerful oxidants (OH) that causes the dye solution to decolorize. Rate constants calculated from color decay versus time reveal a first-order reaction up to 5.0×10-5 mol l-1 in dye concentration. The best experimental conditions were found to be pH 6.0 and 1.0 mol l-1 NaCl when the photoelectrode was biased at +1V (versus SCE). Almost complete mineralization of the dye content (70% TOC reduction) was achieved in a 3-h period using these conditions. Effects of other electrolytes, dye concentration and applied potentials also have been investigated and are discussed. © 2003 Elsevier Science B.V. All rights reserved.

Synthesis of PTSH-modified CeO2 nanoparticles: Effect of the modifier on structure, optical properties, and dispersibility

CeO2 nanoparticles were synthesized by the precipitation method and modified with para-toluene sulfonic acid (PTSH), either in situ or post-synthesis. The presence of PTSH in the samples was confirmed by FTIR. PXRD and FTIR analyses showed that the post-synthesis PTSH modification altered the CeO2 structure, whereas the in situ modification maintained intact the crystalline structure and UV-vis absorbance properties. For both in situ and post-synthesis modifications, TEM images revealed the presence of nanoparticles that were 5nm in size. The dispersibility of the in situ PTSH-modified material in a hydrophilic ureasil-poly(ethylene oxide) matrix was investigated using SAXS measurements, which indicated that CeO2 nanoparticles modified with PTSH in situ were less aggregated within the matrix, compared to unmodified CeO2 nanoparticles. © 2013 Elsevier B.V.

Fish exposure to nano-TiO2 under different experimental conditions: Methodological aspects for nanoecotoxicology investigations

The ecotoxicology of nano-TiO2 has been extensively studied in recent years; however, few toxicological investigations have considered the photocatalytic properties of the substance, which can increase its toxicity to aquatic biota. The aim of this work was to evaluate the effects on fish exposed to different nano-TiO2 concentrations and illumination conditions. The interaction of these variables was investigated by observing the survival of the organisms, together with biomarkers of biochemical and genetic alterations. Fish (Piaractus mesopotamicus) were exposed for 96h to 0, 1, 10, and 100mg/L of nano-TiO2, under visible light, and visible light with ultraviolet (UV) light (22.47J/cm2/h). The following biomarkers of oxidative stress were monitored in the liver: concentrations of lipid hydroperoxide and carbonylated protein, and specific activities of superoxide dismutase, catalase, and glutathione S-transferase. Other biomarkers of physiological function were also studied: the specific activities of acid phosphatase and Na,K-ATPase were analyzed in the liver and brain, respectively, and the concentration of metallothionein was measured in the gills. In addition, micronucleus and comet assays were performed with blood as genotoxic biomarkers. Nano-TiO2 caused no mortality under any of the conditions tested, but induced sublethal effects that were influenced by illumination condition. Under both illumination conditions tested, exposure to 100mg/L showed an inhibition of acid phosphatase activity. Under visible light, there was an increase in metallothionein level in fish exposed to 1mg/L of nano-TiO2. Under UV light, protein carbonylation was reduced in groups exposed to 1 and 10mg/L, while nucleus alterations in erythrocytes were higher in fish exposed to 10mg/L. As well as improving the understanding of nano-TiO2 toxicity, the findings demonstrated the importance of considering the experimental conditions in nanoecotoxicological tests. This work provides information for the development of protocols to study substances whose toxicity is affected by illumination conditions. © 2013 Elsevier B.V..

Produção massal e influência de fatores físicos no cultivo e viabilidade de Bipolaris euphorbiae

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ação da luz ultravioleta e da riboflavina na inativação da Leishmania infantum chagasi em sangue canino conservado em bolsas para transfusão

Pós-graduação em Medicina Veterinária - FMVZ

Influência de gerações de Plutella xylostella (L.) (Lepidoptera: Plutellidae) e de radiação no desempenho de isolados de Bacillus thuringiensis Berliner

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produção de Metarhizium anisopliae (METSCH.) SOROK. e Beauveria bassiana (BALS.) VUILL. em diferentes substratos e efeito da radiação ultravioleta e da temperatura sobre estruturas infectivas desses entomopatógenos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Synthesis and photocatalytic properties of bismuth titanate with different structures via oxidant peroxo method (OPM)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

TiO2/PDMS nanocomposites for use on self-cleaning surfaces

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Filtros UV na água de abastecimento público na região da bacia hidrográfica tietê-jacaré: desenvolvimento de método, estudo de ocorrência e concentrações ambientais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Reassessment of the potential applications of Eu3+-doped Y2O3 photoluminescent material in ceramic powder form

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of water immersion and ultraviolet weathering on mechanical and viscoelastic properties of polyphenylene sulfide-carbon fiber composites

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Produção semissólida de metarhizium anisopliae e beauveria bassiana em diferentes substratos e efeito da radiação ultravioleta e da temperatura sobre propágulos desses entomopatógenos

The present study was aimed to evaluate different (semi-solid) media for the production of Metarhizium anisopliae and Beauveria bassiana propagules, and to evaluate the tolerance of these propagules to ultraviolet radiation and temperature. The experiments were performed at the Biological Control Laboratory of the Instituto Biológico at Campinas, São Paulo, Brazil. For both fungi, 6 repetitions were performed for each of the 17 treatments: corn starch, full rice, parboiled rice, type-1 rice, type-2 rice, oat flakes, canjiquinha [grits], wheat flour, raw cassava flour, yellow corn flour, special wheat flour, corn flour, corn in grains, cassava starch, soy in grains, crushed wheat, and turf. The viability analysis was done in plastic plates containing BDA. For the bioassays involving exposure to ultraviolet light and temperature, BDA was also used for viability analysis, and each treatment was exposed to the UV radiation for 0, 25 and 50 seconds, the temperature exposure being at 20, 25, 30 and 35º C. Using a Potter tower, 2 mL of fungus suspension from each treatment was inoculated to the Diatraea saccharalis caterpillars. Regarding the sporulation, the largest concentrations of M. anisopliae and B. bassiana were found for the treatments with parboiled rice, type-1 rice, type-2 rice, yellow corn flour, corn flour and crushed wheat. The viability of all treatments was superior to 94.00%. Also, the longer the duration of the exposition to the UV, the smaller the number of fertile conidia. At 35o C, a significant loss of conidia viability was observed, and all the treatments presented some level of virulence.