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Membrane acetylcholinesterase activity is considered to be a marker for a cholinergic system. When temporarily expressed in differentiating cells other than the nervous or muscular ones, it may play a role in morphogenesis. In the lichen Parmelia caperata (L.) Ach., acetylcholinesterase is histochemically localized mainly in the cell walls and/or membranes… (More)
Cholinesterase activity has been investigated in Rotifera Bdelloidea (Philodina roseola, Philodina tubercolata, Rotaria rotatoria and other unidentified species) by histochemical methods and in vivo observations. Parallel histological studies have been carried out. The enzyme specificity was tested by employing different substrates and inhibitors. The… (More)
A low-cost biosorbent hybrid material ready for application was obtained in this work. Yerba mate (Ilex paraguariensis) milling residual dust was used as a polyphenol source by ethanolic extraction. Polyphenols were immobilized within a SiO(2) matrix to form an interpenetrated polymer after glutaraldehyde cross-linking. Pb(II), Cr(III) and Cr(VI) were… (More)
This work describes the synthesis of chitosan hydrogel/SiO(2) and chitin hydrogel/SiO(2) hybrid mesoporous materials obtained by the sol-gel method for their use as biosorbents. Their adsorption capabilities against four dyes (Remazol Black B, Erythrosine B, Neutral Red and Gentian Violet) were compared in order to evaluate chitin as a plausible replacement… (More)
In the lichen Parmelia caperata (L.) Ach. the distribution pattern of membrane-bound Ca2+ is investigated in the symbionts by chlorotetracycline (CTC)-induced fluorescence during the development of propagative structures, the soredia. The results demonstrate that Ca2+ accumulation in the alga and the fungus is associated with this morphogenetic process;… (More)
The concept of chordates arose from the alliance between embryology and evolution in the second half of the nineteenth century, as a result of a theoretical elaboration on Kowalevsky's discoveries about some fundamental similarities between the ontogeny of the lancelet, a putative primitive fish, and that of ascidians, then classified as molluscs. Carrying… (More)
Characteristics of a simple and compact spectral light source for obtaining the spectra of highly ionized gases are presented. Krypton and xenon spectrograms have been produced which show spectral lines belonging to a high degree of ionization.
New Kr VIII spectroscopic results between 280 and 2000 A using a theta-pinch and a discharge tube are presented, including one new energy level and two new classified lines. The previous analysis was also revised, and the uncertainty in the resulting level values is now <10 cm(-1).