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Abstract  

Prompt gamma-neutron activation analysis, PGNAA, has been used to determine major and minor elements of bituminous coals. Calibration curves for H, C, N, Cl, Si, Ti, Al, Fe, Ca, Na, K, and S were obtained using six coals of different origin. The correlation coefficients are, in general, greater than 0.9 with the exception of C, N, and K. The -peak intensities were corrected for volume hydrogen content and normalised to the source intensity by using the 2615 keV -line from the (n, n ) reaction induced in the lead container of the Cf source. Elemental compositions of new coal samples were determined. In spite of the weak neutron source intensity, the comparison between the elemental concentrations measured by PGNAA and by conventional analysis show good agreement except for N, K, S and Ca.

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Abstract  

A simulation study of a PGNAA measuring arrangement with a252Cf neutron source for the characterization of cement raw materials was carried out using the MCNP code to investigate the effect on the system response of varying the bulk density and the water contentv w of samples of fixed dry composition. The source is placed at the centre of a lead cylinder of extemal radiusR Pb. This cylinder is enclosed in a coaxial cylinder of polyethylene moderator of extermal radiusR in. The sample material is confined to the space between an outer cylindrical surface of radiusR out and the moderator cylinder. The first series of simulation runs was carried out for different sets of values ofR in,R out and , and constantv w. The system specific responseS (count rate per wt%) shows a broad maximum aroundT M=R in-R Pb=4 cm andT S=R out-R in=8.5 cm and a dependence on that is almost linear in the region of the maximum. In a second series of runs the dependence ofS onv w was studied for a geometry corresponding to a real experiment described elsewhere and for a geometry for which the density saturation effect is already apparent. It is shown that when the sensitivity of the system is optimized both andv w must be used as calibration parameters while in the low-sensitivity design regionv w can be used as the only calibration parameter.

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Summary This paper studies annihilating properties of operators generated by spherical convolution over the unit sphere O2q of Cq. Its specific aim is to answer the following question: given a complex number ?, |?|=1, to determine what functions of L 2(O2q) have zero average over every section  Ow ?,q  :={ z ?O2q: <z,w> = ?} of O2q . Here, <.,.>stands for the usual inner product of Cq.

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Abstract  

Data are presented for210Po levels in edible parts of marine species significant in the diet of the Argentine population. The sample collection sites were situated between 35° and 45° S in the Atlantic Ocean. The specific activities obtained, expressed per wet veight and with a 95% confidence level, ranged between 31.3±9.1 mBq kg–1 for pollack (Genypterus blacodes) and 1790±280 mBq kg–1 for squid (Illex argentinus). Hake (Merluccius hubbsi) followed by squid are the major contributors to the dose. The annual committed effective doses were 0.7 mSv and 0.6 mSv and the effective collective doses were 24 man·Sv and 20 man·Sv, respectively, for these species. For the remainder, because of both their low consumption rates and low specific activities, the corresponding doses were negligible compared with the former.

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Abstract  

This paper describes experimental results through multivariate statistical methods that might reveal outliers that are rarely taken into account by analysts. The results were submitted to three procedures to detect outliers: Mahalanobis distance, MD, cluster analysis, CA, and principal component analysis, PCA. The results showed that although CA is one of the procedures most often used to identify outliers, it can fail by not showing the samples that are easily identified as outliers by other methods, like MD. Mahalanobis distance proved to be the simpler application, with sensitive procedures to identify outliers in multivariate datasets.

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Abstract  

In this study, bromine (Br), chlorine (Cl), potassium (K) and sodium (Na) were measured in the blood of Brazilian inhabitants from Southeast (S) and Northeast (N) regions. A reference range was established as a function of sex and considering lifestyle factors (non-smokers and non- drinkers). For both regions lower values of K were found in females when compared to males and lower values of Na were found in males compared to females. Increasing trends for Na and Br were observed in the Northeast region.

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Abstract  

Instrumental neutron activation analysis (INAA), have been used for the definition of compositional groups of potteries from Justino site, Brazil, according to the chemical similarities of ceramic paste. The outliers were identified by means of robust Mahalanobis distance. The temper effect in the ceramic paste was studied by means of modified Mahalanobis filter. The results were interpreted by means of cluster, principal components, and discriminant analyses. This work provides contributions for the reconstruction of the prehistory of baixo São Francisco region, and for the reconstitution of the Brazilian Northeast ceramist population of general frame.

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Summary  

Neutron activation analysis, using Au as flux monitor, was applied to determine the concentrations of Br, Cl, K and Na in blood of healthy male and female blood donors, selected from blood banks and hematological laboratories from different regions of Brazil. The aims of this study were to collect more reference values of the Brazilian population as well as to perform hematological investigations. The advantages as well as the limitations of using this nuclear procedure are discussed.

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Abstract  

Polyurethane composites with bagasse of sugar cane (BSC) at different proportions: 5, 10 and 20 mass/mass% were prepared by melt mixing method. The thermal behavior of these composites were studied by thermogravimetry (TG/DTG). The influence of fiber concentration on the kinetic parameters of the composites was studied and a better interaction was suggested between PU/BSC with 5mass/mass% of fiber. Scanning electron microscopy was carried out to investigate surface morphology.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Basheer, Denise Oliveira, P. Volpe, and C. Airoldi

Abstract  

A structure-activity relationship study (SAR) was applied to correlate the biological activities of m-alkoxyphenol compounds on Chromobacterium violaceum respiration with chemical structure properties. The biological activities of these compounds on metabolism rates were obtained through microcalorimetry. The calculations to estimate several physicochemical properties were carried out at the semi-empirical AM1 and ab initio DFT levels using the CEP-31G basis set and were parameterized using the continuum-solvation model COSMO for solvent contribution. m-alkoxyphenols properties were evaluated by chemometric analyses to carry out a correlation between the physicochemical properties and their biological effects. These compound effects increase with lateral hydrocarbon chain length, volume, dipole moment, proton affinity, energies of HOMO and LUMO, partition coefficient and enthalpy of formation and decrease with solvent effects and ionization enthalpy.

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