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

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)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. (C) 2010 American Institute of Physics. [doi:10.1063/1.3529422]13324Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

CONSTRUCTION OF A DIFFERENTIAL ISOTHERMAL CALORIMETER OF HIGH SENSITIVITY AND LOW COST.

CONSTRUCTION OF A DIFFERENTIAL ISOTHERMAL CALORIMETER OF HIGH SENSITIVITY AND LOW COST The high cost of sensitivity commercial calorimeters may represent an obstacle for many calorimetric research groups. This work describes (fie construction and calibration of a batch differential heat conduction calorimeter with sample cells volumes of about 400 mu L. The calorimeter was built using two small high sensibility square Peltier thermoelectric sensors and the total cost was estimated to be about US$ 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 K3261651165

The Violacein Biosynthesis Monitored by Multi-Wavelength Fluorescence Spectroscopy and by the PARAFAC Method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Obtaining information about a biosynthetic pathway is a complex and laborious procedure. In this sense, this work presents a new approach for the initial analysis of the biosynthesis of fluorescent natural products using as example the violacein biosynthesis. For this, a culture of Chromobacterium violaceum was grown in a bioreactor from which aliquots were collected every 2 h for subsequent analysis by multi-wavelength fluorescence spectroscopy. The excitation-emission matrices demonstrated the dynamic behavior of the fluorophores signal that are consumed and produced by the bacterium. These signals were resolved by PARAFAC (parallel factor analysis) method totalizing six pure components. Tryptophan and violacein were identified by comparison to spectra available in the literature. The identification of other fluorophores was critical step due to the lack of a database of fluorescent natural products to compare spectra. Finally, this methodology has great potential to achieve a deeper insight into the biosynthesis of natural products.231120542064Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Adsorption of alkyl p-hydroxybenzoates from aqueous solution onto teflon

Earlier evidences for the adsorption of a homologous series of alkyl p-hydroxybenzoates onto Teflon are confirmed by direct measurements. The kinetic analysis suggests that the adsorption occurs via two consecutive processes: flat adsorption followed by the solute reorientation at the polymer surface. The adsorption isotherms confirm that the strength of interaction increases with the solute hydrophobicity, An increased wettability of the Teflon surface was also observed to occur parallel to the adsorption, suggesting the presence of some oriented solute molecules which reduce the interfacial tension between the polymer and water. (C) 1996 Academic Press, Inc.179132232

INTERACTION OF ALKYL P-HYDROXYBENZOATES WITH MICELLES - EVALUATION OF THEIR PARTITION-COEFFICIENTS AND IONIZATION-CONSTANTS

154236937

Measurements of the Molar Heat Capacities and Excess Molar Heat Capacities for Water plus Organic Solvents Mixtures at 288.15 K to 303.15 K and Atmospheric Pressure

Experimental molar heat capacity data (Cp(m)) and excess molar heat capacity data (Cp(m)(E)) of binary mixtures containing water + (formamide or N,N-dimethylformamide or dimethylsulfoxide or N,N-dimethylacetamide or 1,4-dioxane) at several compositions, in the temperature range 288.15 K to 303.15 K and atmospheric pressure, have been determined using a modified 1455 PAAR solution calorimeter. The excess heat capacities are positive for aqueous solutions containing 1,4-dioxane, N,N-dimethylformamide or dimethylsulfoxide, negative for solutions containing water + formamide and show a sigmoid behavior for mixtures containing water + N,N-dimethylacetamide, over the whole composition range. The experimental excess molar heat capacities are discussed in terms of the influence of temperature and of the organic solvent type present in the binary aqueous mixtures, as well as in terms of the existing molecular interactions and the organic solvent's molecular size and structure.39225927

POTASSIUM CATION EXTRACTION OF A SODIUM-CHLORIDE SATURATED SOLUTION USING THE LIQUID MEMBRANE LESSON

Extraction of potassium ion from an alkaline source phase containing high concentration of sodium ion through a chloroform phase facilitated by the lipophilic carrier crown ether 2-sym-(dibenzo-19-crown-6-oxy) decanoic acid was studied at 298 K by bulk liquid membrane and by liquid surfactant membrane experiments. Differences in the transport rate and efficiency were observed and discussed for the two separation techniques.18544044

Microcalorimetry: A useful technique for studying the diauxism of Saccharomyces cerevisiae.

In this work we first introduce the reader to the basic concepts of biology, bioenergetics and biochemistry, concerning the area of cell biology. Then we explain what diauxism is and an example of this phenomenon, applied to S. cerevisiae, is presented. Finally, thermograms obtained by microcalorimetry, from S. cerevisiae that undergo diauxism, are discussed from a biochemical point of view.23225726

Thermodynamic and Kinetic Studies of Glucose Mutarotation by Using a Portable Personal Blood Glucose Meter

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A thermodynamic and kinetic study of the mutarotation reaction of D-glucose in aqueous solution was carried out using a portable personal blood glucose meter. This physical chemical experiment is proposed as an alternative to classical polarimetry. The glucose meter allows the indirect monitoring of the mutarotation process in water, by using an enzymatic redox reaction. The test strips of the glucose meter contain glucose dehydrogenase which converts beta-D-glucose into D-glucolactone. This reaction selectively converts glucose and generates an electrical current in the glucose meter which is proportional to the glucose concentration. This experiment allows the teacher to explore the kinetics and thermodynamics of the mutarotation of D-glucose and, moreover, the stereospecificity of enzymatic reactions.561209214Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq