RESUMEN
Results of the simultaneous in-situ UV-vis and open-circuit potential (OCP) monitoring of the low-concentrated aniline (An) polymerization in the presence of camphorsulfonic acid (CSA) suggested that during the induction period (IP) step a transition state formed, which probably included anilinium cation and the oxidant anion, antecedent to a propagation step. No aniline oligomers were registered at this stage but they appeared at the beginning of the propagation step under the investigation conditions. The moments of formation of insoluble pernigraniline phase and appearance of emeraldine units in the growing pernigraniline chains were ascertained by the comparison of kinetic and OCP profiles of the polymerization process both in the solution and in SiC dispersion water mediums. It is deduced that pernigraniline reduction by aniline molecules begins earlier than it is generally accepted (i.e., earlier than OCP maximum is reached) and probably in parallel to a continuing appearance of pernigraniline units even in the same chains that undergo the reduction. It was found that an addition of the SiC dispersion phase into the polymerization mixture accelerates differently all stages of the aniline polymerization. Finally, this polymerization process leads to the formation of polyaniline (PANI)-CSA shell with thickness in the range from 0.5 nm to a few nm at the SiC nanocrystals surface.
Asunto(s)
Compuestos de Anilina/química , Compuestos Inorgánicos de Carbono/química , Compuestos de Silicona/química , Biofisica/métodos , Alcanfor/química , Cationes , Química Física/métodos , Cinética , Nanoestructuras/química , Nanotecnología/métodos , Oxidantes/química , Polímeros/química , Espectrometría Raman , Ácidos Sulfónicos/química , Factores de Tiempo , Agua/químicaRESUMEN
The analysis of the literature and authors' data concerning the mechanism of antioxidant protection of the organism under conditions of "oxygen stress" is submitted. Possible mechanisms of initiation of free radical reactions with participation of oxygen and the role of hydroxyl radicals, being one of the basic factors, determining toxic action of oxygen, are considered. The methods of estimation of antiradical activity of biologically active compounds are characterized.
Asunto(s)
Antioxidantes/farmacología , Estrés Oxidativo/efectos de los fármacos , Animales , Radicales Libres/efectos adversos , Radicales Libres/metabolismo , Radicales Libres/farmacología , Humanos , Radical Hidroxilo/efectos adversos , Radical Hidroxilo/metabolismo , Radical Hidroxilo/farmacología , Especies Reactivas de Oxígeno/efectos adversos , Especies Reactivas de Oxígeno/metabolismo , Especies Reactivas de Oxígeno/farmacologíaRESUMEN
Antiradical and antioxidative activities of dieton, phoridon, niphedipin, phlamicar, mildronat in vitro were studied by spectrophotometer's method with the use of dyfenilpycrilgydrasil and method of pulse voltametry. Also influence of drugs was studied under antioxidative insufficiency (AOI), which had modelled by exclusion of alpha-tocopherol from the animal's ration.