Carlos Eduardo Perles

Communication: Evidence of hydrated electrons injected by a metallic electrode in a high voltage system

In this work it a strong evidence of the hydrated electrons production was shown in a film of condensed water, by directing the injection of electrons in localized and/or delocalized water electronic states using a system of high voltage made in laboratory. The results show that the water layers on the silica particles are electrically charged by injection of electrons from a metal electrode when silica is placed in high electric field. This charging process also appears to depend on the thickness of these water layers and of the spatial arrangement required by the silica surface.

Calorimetric study of the antibacterial activity of sodium n-alkylsulfates on the metabolism of Chromobacterium violaceum

The bioactivity of a series of sodium n-alkylsulfates (C6-C10 and C12) was studied with flow calorimetry to follow in real time the calorimetric effect on the metabolic rate of the bacterium Chromobacterium violaceum. All the compounds showed a linear plot of the fraction of control metabolic heat rate against log (dose). From these plots the value of dosemax (the dose producing zero metabolic heat rate) for each compound was evaluated. The value of dosemax is correlated with the chain length of the molecule, showing that their biological activity is directly proportional to the lipophilicity of the compound.

Electrostatic charging and charge transport by hydrated amorphous silica under a high voltage direct current electrical field

This work was initially based on the casual observation of an electrostatic phenomenon, in which particles of amorphous silica were attracted by a dc electrical field. The first observations were recently shown in a communication in this journal. To explain the electrical charge transport process observed in this work, all forces acting on silica particles were estimated and the significant ones were used to formulate a model made up of three elementary steps. Analyzing the experimental observations using this model, it was possible to suggest that electrons can be introduced into and removed from electronic bands of water.

Construção de um calorímetro isotérmico diferencial de alta sensibilidade e baixo custo

The high cost of sensitivity commercial calorimeters may represent an obstacle for many calorimetric research groups. This work describes the construction and calibration of a batch differential heat conduction calorimeter with sample cells volumes of about 400 μL. The calorimeter was built using two small high sensibility square Peltier thermoelectric sensors and the total cost was estimated to be about US

Propriedades físico-químicas relacionadas ao desenvolvimento de membranas de Nafion® para aplicações em células a combustível do tipo PEMFC

500. The calorimeter was used to study the excess enthalpy of solution of binary mixtures of liquids, as a function of composition, for the following binary systems of solvents: water + 1,4-dioxane or + dimethylsulfoxide at 298,2 ± 0,5 K.