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Abstract  

Instrumental neutron activation analysis (INAA) is a well-known analytical method for nondestructive, sensitive and accurate determination of elemental composition of geological samples. In the present work twenty-two elements were determined by INAA in nine rhyolitic geological samples from a wolframium ore body Lela, located in the territory of Isla de la Juventud, Cuba. The obtained results are important for the preliminary geochemical evaluation of the studied rocks.

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Abstract  

Instrumental neutron activation analysis (INAA) and gamma spectrometric analysis (GSA) were used for the determination of twenty-one elements in pegmatites of Loma Venturilla area, in Central Cuba. The application of both methods allowed the determination of K, Co, Cr, Sc, Rb, Cs, Ba, Ta, Hf, Th, U, La, Ce, Nd, Sm, Eu, Tb, Ho, Tm, Yb and Lu. The results were obtained with good precision and accuracy. The knowledge of such concentrations is particularly useful for geochemical investigations. The obtained concentration values can be used in studies on the petrogenesis of those rocks. The results facilitate the evaluation and estimation of the main process involved in the generation and differentiation of the melts from which the pegmatites were formed.

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Abstract  

Se in Ni and Co concentration in concentrates obtained from the nickel industry has to be determined for quality control requirements in their commercialization. Analysis of Se at minor and trace levels is relatively complicated and destructive procedures are frequently required. In this work the determination of Se by epithemal neutron activation analysis (ENAA) in 17 samples from Cuban nickel industry was investigated. Application of ENAA allowed nondestructive determination of Se concentration down to ppm level in spite of the presence of high Co, Fe, Ni and Cr contents in the samples. For attenuation of the thermal neutron flux a Cd filter was utilized.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
G. Rodríguez
,
A. Rivero
,
J. Bermúdez
,
S. Guevara
,
J. Insfrán
, and
G. Zayas

Abstract  

In this work the determination of elemental composition of MIBI, MAG-3 and sodium phytate by INAA was investigated. Analytical information about the concentration and/or detection limits of some toxic elements (Hg, Cd, As, Se, Sb) and other trace element of interest (Fe, Cr, Co, Zn, Br) was obtained.

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Acta Physiologica Hungarica
Authors:
Cristina Sánchez López
,
C. Barriga
,
A. Rodríguez
,
L. Franco
,
M. Rivero
, and
J. Cubero

We describe a chronobiological study of the effects of the oral administration of the essential amino acid L-methionine to common quail ( Coturnix coturnix ). This amino acid is a precursor of the neurotransmitter acetylcholine which is responsible for controlling and maintaining wakefulness through the ventrolateral pre-optic area of the hypothalamus and controlling the REM sleep in the nucleus reticularis pontinus oralis (NRPO). The quail model was chosen as these birds are monophasic and active by day, as are humans. The animals were kept under a constant 12h:12h light/dark cycle, fed ad libitum and housed in separate cages equipped for activity recording. Methionine was administered daily (1 h before lights off) for 1 week (chronic treatment), with the birds divided into 4 groups: a capsule with 15 mg of L-methionine (Met15 treatment group); a capsule with 30 mg of L-methionine (Met30 treatment group); a capsule with methylcellulose as excipient (control group); no capsule (basal group). In addition, we compared the first day of treatment (acute experiment) with the basal and control results. Actimetry (DAS24©) was used to quantify the activity data, and the sleep/wake rhythm was analyzed using the Ritme© software package. The statistical analysis of the activity data was descriptive (± SD) and inferential (Tukey test). The data showed increased (p<0.05) mean diurnal activity pulses in the Met30 group versus the other groups in both the acute and the chronic experiments. No changes were found in nocturnal activity. The chronobiological analysis showed a significant increase in the MESOR parameter of the Met30 group in both chronic and acute experiments versus the other groups. The acrophase showed no significant changes, in all groups being at around 13:45 h. In conclusion, the oral administration of L-methionine increased diurnal activity; probably due to the stimulating neuromodulatory action of acetylcholine.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
G. Capote Rodriguez
,
R. Padilla Alvarez
,
G. Pérez Zayas
,
A. Hernández Rivero
,
M. López Reyes
,
S. Ribeiro Guevara
, and
J. Molina Insfrán

Abstract  

Thirty elements were determined by INAA in Cuban soil samples collected in 17 zones from western regions of Cuba, which were affected by neuropathy epidemic in 1992. The presence of toxic elements was evaluated to provide data for the analysis of possible paths of intoxication through local agriculture product consumption. The results obtained for As, Th and U are compared with similar data reported on literature.

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