RESUMO
Copper nanoparticles loaded inside or outside carbon nanotubes (CNTs) were prepared by a simple wet chemistry method. The structures and physicochemical properties of the obtained materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Methyl acetate (MA) hydrogenation forming methanol and ethanol was chosen as the application to explore the catalytic performances of copper inside and outside CNTs. The reaction results indicated that the catalytic activity of Cu-inside-CNTs catalyst was significantly higher than that of Cu-outside-CNTs because of the space confined effects. Furthermore, the influences of Cu content on CNTs to the catalytic performance were also investigated.
RESUMO
The fern Athyrium yokoscense is known to be highly tolerant to lead toxicity, and is a lead hyperaccumulator that can accumulate over 1,000 microg g(-1) of lead in its dry matter. In this work, we examined whether the gametophytic generation of A. yokoscense also resists lead toxicity like the sporophytic generation. Spore germination in A. yokoscense was more tolerant to Pb2+, compared to that in other fern species, such as Pteridium aquilinum, Lygodium japonicum and Pteris vittata. In addition, the early gametophyte development of A. yokoscense was not much affected by 10 microM Pb2+, as evaluated from the prothallial growth and rhizoid development. We also showed that Athyrium gametophytes could accumulate more than 10,000 microg g(-1) of lead, and that the lead was localized in the cytosol and vacuole of rhizoidal cells, as determined by a transmission electron micrograph. These results indicate that Athyrium gametophytes have the ability to accumulate lead in the rhizoids. Furthermore, the gametophytes were found to include a large amount of proanthocyanidins (condensed tannins). Because proanthocyanidins have a latent ability to complex with lead ions, the possible roles of proanthocyanidins in the lead tolerance and accumulation of Athyrium gametophytes are discussed.
