Search Results

You are looking at 1 - 9 of 9 items for

  • Author or Editor: E. Leite x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

Among the numerous heavy ion reactions, those of potential interest for chemical analysis can be identified based on their Q values, Coulomb barriers, and threshold energies. A simple computer code has been written for these calculations. The use of the calculated data is illustrated with a survey of the possibilities of HIAA with N+, Li+, B+, Be+ and C+ beams yielding radioisotopes with half-lives of 10 to 104 sec.

Restricted access

Rutherford backscattering with heavy ions

Part II: Sensitivities and applications

Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Sullins, C. Barros Leite, and E. Schweikert
Restricted access

Rutherford backscattering with heavy ions

Part I: Mass and depth resolution

Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Sullins, C. Barros Leite, and E. Schweikert
Restricted access

Abstract  

The color efficiency of ceramic glaze blue pigments obtained by the Pechini method was presented in this work. The fired pigments and enameled samples were characterized by thermogravimetry (TG) and differential thermal analysis (DTA), XRD, UV-VIS-NIR spectroscopy and CIE-L*a*b* color-measurements. The pigments obtained by the Pechini method present a better solubility in the molten glazes than the pigments obtained by the mechanical mixture of the precursor oxides.

Restricted access

Abstract  

A graphical method was developed to relate data from Rutherford backscattering spectrometry to sample characteristics, such as thickness and concentration profiles. The method was then applied to analyze these characteristics of a gold film.

Restricted access

Abstract  

The aim of this work was to obtain membranes from polyamide 6/montmorillonite clay nanocomposites through the phase inversion technique. The nanocomposites and membranes from polyamide 6/montmorillonite clay were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). Microporous and asymmetric membranes were successfully obtained from nanocomposites and the results showed that the salts were incorporated by intercalation between the organoclay layers and, apparently that the nanocomposites and membranes were thermally more stable than the pure polyamide.

Restricted access

Abstract  

The accuracy of the quantitative analysis of thick targets by XRF is impaired by effects due to the absorption of X-rays in the matrix associated with the non-uniformity of the X-ray beam and the lack of knowledge of the actual distribution of trace elements in the target. The uncertainty in the elemental mass associated to a definite number X-rays detected is discussed in the paper. A correction factor is derived to account specifically for the effect of the absorption of X-rays and the non-uniformity of the X-ray beam.

Restricted access

Abstract  

The synthesis and the characterization of Al2O3-based nanocrystalline inorganic pigments are reported. The pigments were synthesized by the polymeric precursor (Pechini method) using Cr2O3 as chromophore. XRD results only evidenced the corundum phase. The average particle size was about 34 nm. The samples were also characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG), and CIE-L*a*b* calorimetry. The pigments obtained in this work presented different colors, ranging from green to rose.

Restricted access
Journal of Flow Chemistry
Authors: Ingrid C. R. Costa, Ivaldo Itabaiana Jr., Marcella C. Flores, Ana Clara Lourenço, Selma G. F. Leite, Leandro S. de M. e Miranda, Ivana C. R. Leal, and Rodrigo O. M. A. de Souza

Abstract

The use of glycerol derived from biodiesel industry is an important development to add value to this actual waste. Several products can be obtained from glycerol, but acetins are very interesting molecules with a wide range of applications in pharmaceutical, cosmetics, food, and fuel industry. Herein we report our results on biocatalyzed batch and continuous-flow process for valorization of glycerol derived from biodiesel industry towards acetin production. Excellent results can be obtained with different selectivities depending on the nature of glycerol used and reaction conditions being able to produce monoacetin, diacetin, or triacetin depending on the reaction condition.

Restricted access