Descripción: Yerba maté extracts have in vitro antioxidant capacity attributed to the presence of polyphenolic compounds, mainly chlorogenic acids and dicaffeoylquinic acid derivatives. DPPH is one of the most used assays to measure the antioxidant capacity of pure compounds and plant extracts. It is difficult to compare the results between studies because this assay is applied in too many different conditions by the different research groups. Thus, in order to assess the antioxidant capacity of yerba maté extracts, the following procedure is proposed: 100 μL of an aqueous dilution of the extracts is mixed in duplicate with 3.0 mL of a DPPH 'work solution in absolute methanol (100 μM.L-1), with an incubation time of 120 minutes in darkness at 37 ± 1 °C, and then absorbance is read at 517 nm against absolute methanol. The results should be expressed as ascorbic acid equivalents or Trolox equivalents in mass percentage (g% dm, dry matter) in order to facilitate comparisons. The AOC of the ethanolic extracts ranged between 12.8 and 23.1 g TE % dm and from 9.1 to 16.4 g AAE % dm. The AOC determined by the DPPH assay proposed in the present study can be related to the total polyphenolic content determined by the Folin-Ciocalteu assay.

Descripción: Group of microstructures present in the Ordovician Yerba Loca and Los Sombreros Formations (cropping out in the vicinity of Road 150, between cuesta del Viento and Los Túneles), are described and interpreted. Cleavage, joints and fractures, shear zones, planar and sigmoid (en echelon) veins and kink bands are most common among them. Folded and domino faulted quartz veins, resulting from pressure solution contraction during formation of axial plane cleavage, are an outstanding feature and allowed calculation of contraction associated to cleavage development. The assemblage of minor structures shows coherency with the major structures hosting them and evidences a systematic displacement and stacking of rock masses from west to east. They also show the important participation of pressure solution and re-crystallization processes during deformation, along with progressive deformation due to rotation of local structures in the regional stress field.

Descripción: Structures cropping out in the Jachal Valley from the Cuesta del Viento dam to the locality of Los Tuneles are described and analyzed. These structures affect the Ordovician Yerba Loca and Los Sombreros Formations and the Paleogene-Neogene Vallecito and Rodeo Formations. The oldest units form the heights, Sierra Negra de Rodeo and Sierra de los Túneles, which are limited in their eastern flanks by the La Tranca and Los Blanquitos overthrusts, and by the angular unconformity underlying Rodeo Formation in their western ones. The regional folds show asymmetrical shapes and a wavelength comparable to the width of the Sierras, but minor structures ranging from meters to tens of meters are very common in their eastern limbs. Regional folds axis trend varies from Az 315 to Az 360 and the vergence of pre-carboniferous and andean structures point to the east, what makes very difficult to use orientation as a criterion to discriminate the differentiated deformational episodes. The comparison of sedimentological and structural features in the Rodeo area with those at the San Juan River evidences strong similarities but also important differences. Among the first ones, it can be mentioned the lithological and structural resemblance of the Ordovician units, which show NS trending axis in the eastern outcrops and point N-NW in the western ones. Main differences are the absence -in the Rodeo area- of the metapelites of the Silurian Calingasta Formation. and that of the conglomerates and rhythmites of the Devonian (?) El Planchón Formation. present in the San Juan River section.