Correlação entre a estrutura atômica superficial e o processo de adsorção-dessorção reversível de hidrogênio em eletrodos monocristalinos Pt(111), Pt(100) e Pt(110)

Platinum is widely used as electrode in electrocatalytic processes, however the use of polycrystalline electrodes introduces a series of variables in the electrochemical system due to the aleatory contribution of all the crystallographic orientations with different surface packing of atoms. Single crystal platinum electrodes of low Miller index present surface structure of high regularity and serve as model to establish a correlation among the macroscopic and microscopic properties of the electrochemical interface. Therefore, the main aim of this work is the study of the voltammetric profiles of the reversible adsorption-desorption of hydrogen on Pt(100), Pt(110) and Pt(111), in order to correlate the electrochemical properties of each different orientation with the surface atomic structure.

Citotoxicity of food dyes sunset yellow (E-110), bordeaux red (E-123), and tatrazine yellow (E-102) on Allium cepa L. root meristematic cells

The objective of this study was to evaluate the cytotoxic effect of the food dyes sunset yellow, bordeaux red, and tartrazine yellow on the cellular cycle of Allium cepa L. Each dye was evaluated at the doses of 0.4 and 4.0 mL, at the exposure times of 24 and 48 hours in root tip cells of Allium cepa L. Slides were prepared and cells were analyzed during the whole cell cycle for cellular aberrations totaling 5,000 total cells for each dose evaluated. The mitotic index was calculated, and statistical analysis was performed using the Chi-squared test (p < 0.05). The results showed that the three dyes used under the evaluated doses and exposure times were cytotoxic to the cells of the system-test used. Further cytotoxicity studies should be conducted for additional results and a proper evaluation of the effect of these three dyes on a cellular level.