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R Luzzi

Publications and source records attributed to R Luzzi.

At least 19 recordsLinked to original sources

Optical properties of nonequilibrium low-dimensional systems

The optical properties of low-dimensional carrier systems ("quantum wire" type) driven away from equilibrium are studied. The frequency and wave-vector-dependent dielectric function of a quasi-one-dimensional electron system under the action of an exciting external pumping source is derived. The optical responses of the system are obtained in terms of its nonequilibrium thermodynamic state, the latter characterized resorting to a nonequilibrium statistical ensemble formalism.

Journal Article↗

Antinociceptive activity of a hydroalcoholic extract obtained from aerial parts of Sebastiania schottiana (Euphorbiaceae).

This study analyzed the antinociceptive effects of a hydroalcoholic extract obtained from the aerial parts of Sebastiania schottiana, a Brazilian medicinal plant used to treat various painful diseases. For this purpose, the writhing test, capsaicin and formalin induced-pain in mice were used. The results showed that the hydroalcoholic extract exhibited considerable antinociception in all the models studied, being more potent than aspirin.

Acetates↗

[Hemostatic and structural effects of the lyophilized cellulose sponge].

Hemostatic effects of oxidized cellulose (Surgicel) are well known. Based on a possible similar effect of a sponge obtained after lyophilization of biosynthetic cellulose, two different experimental studies were planned. Phase I-Pieces of cellulose sponge were inserted into small provoked cortical wounds of twelve dogs. The time elapsed to obtain bloodstill after cortical damage and application of cellulose was observed in every dog, searching to detect any possible hemostatic effect of the material. The animals were sacrificed after 7, 30 and 90 days. An average time of 1 minute was elapsed until bleeding control was achieved. No clinical adverse effect was noticed. Microscopy showed histiocytic and mild foreign body reaction at 7 days, which diminished at 30 days. Almost no reaction surrounded the implant at 90 days. Lyophilized cellulose has a peculiar eosinophilic appearance, composed by thin irregular filaments which diminished their thickness with the time. At 90 days only sparse irregular cellulose filaments could be detected. Phase II-Small equal sponge fragments were inserted in the liver of twelve rats and observed 7, 30 and 90 days. At autopsy, small peritoneal adhesions were noticed at 30 and 90 days. Microscopy showed intense histioplasmocytic and foreign body reaction in all animals mainly at 7 days. In two animals, refringent intracellular cellulose particles were evident inside giant foreign body cells after 90 days. This fact evidences that cellulose can be reabsorbed by phagocytic phenomena when implanted in mammalians. A comparative group with other hemostatic material and the same method must be done to clarify the issue of hemostatic effects of this membrane.

Animals↗

On Fröhlich's coherent effects in biological systems: influence of carriers and high order dissipative effects.

Following Fröhlich we consider a system that models a biological one, for example, a long chain of proteins possessing polar modes of vibration and where energy is pumped through metabolic processes. We consider the effect produced by free electrons that are usually present as hole carriers in proteins with electron-donor molecules. A theory of relaxation based on the non-equilibrium statistical operator method is used in the derivation of the kinetic equations to introduce non-linearities due to interactions of the polar vibrations with the carriers and with a thermal bath. These non-linearities arising from high order relaxation processes lead to the emergence of the Fröhlich effect in the polar modes, i.e. the occurrence of a (non-equilibrium) Bose-Einstein-like condensation. It points to an instability of the system that seems to be followed by a morphological transformation in the form of a spatially ordered dissipative structure.

Biophysical Phenomena↗