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  • Author or Editor: M. González Garcia x
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Abstract  

In the present work a study was made for determining colour intensities using as luminous non-monochromatic source the Cherenkov emission produced in the walls of a glass capillary which acts as luminous source itself inside of a coloured solution to be evaluated. The reproducibility of this method has been compared with the spectrophotometric assay; the relative errors of both analytical methods have been calculated for different concentrations of congo red solution in the range of minimal error, according to Ringbom's criterion. The sensitivity of this analytical method has been studied for the two β-emitters employed:90Sr/90Y and204Tl.

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The thermal behaviour of [CoCO3(NH3)4]2SO4 · 3H2O was studied using X-ray diffraction diagrams, DTA, TG and heating at constant temperatures for different periods of time. The X-ray study was made in order to characterize with the powder diagrams the phases obtained and to follow the reactions of the complex when heated in air up to 800‡. A parallel infrared spectral study was also made. The results obtained by the various experimental methods were compared with the theoretical weight losses.

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The effectiveness of five commercial disinfectants used in the food industry was evaluated against different strains isolated from foodborne outbreaks (E. coli O157:H7, Salmonella spp. and L. monocytogenes) and a collection strain (S. aureus) in an aqueous suspension medium. The disinfectants evaluated included quaternary ammonium compounds, aldehydes, hydrogen peroxide and peracetic acid, clorhexidine and a tertiary alkylamine.  In the absence of organic matter, all the disinfectants tested were effective with an exposure time of 10 min at the lowest concentration recommended by the manufacturer. However, in the presence of organic matter their effectiveness decreased. The most effective disinfectant against pathogenic bacteria tested was a quaternary ammonium compound based disinfectant combined with non-ionic surfactants, polyphosphates and alkaline salts. The least effective ones were disinfectants containing tertiary alkylamine, peracetic acid and hydrogen peroxide.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Azahra, J. López-Peñalver, M. Camacho-García, C. González-Gómez, T. El Bardouni, and H. Boukhal

Abstract  

Aerosols samples in near-surface air of Granada (Spain) were collected on a weekly basis. The seasonal 210Pb and 7Be concentrations were determined during the five-year period, from October 1993 to September 1997. The elements, despite their different origin and their different distribution throughout the atmosphere, present the same seasonal variation. There was a tendency for a maximum during the summer season and a minimum during fall and/or winter. In this work, the concentration of 7Be and 210Pb and meteorological data have been used in order to determine the periods of the potential radioactive pollution. This study, also, shows that the deposition of 7Be occurs primarily by precipitation except during the investigation periods where precipitation was scarce and irregular.

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The aim of this research was to assess the total antioxidant activity (TAA) of lipophilic (Lextr) and hydrophilic (Hextr) tomato extracts using in vitro chemical tests and cell-based assays, focusing on possible synergistic actions between tomato antioxidants. Both Hextr and Lextr were HPLC analysed for their carotenoids, phenolic compounds, and ascorbic acid contents. For the evaluation of TAA, extracts were assayed alone or in combination using in vitro chemical tests (TEAC, FRAP) and cell-based (CAA) assays using human hepatoma (HepG2) and human histiocytic lymphoma (U937) cells. The only carotenoid detected in Lextr was lycopene, while a mixture of phenolic compounds (chlorogenic acid, caffeic acid, and rutin) was identified in Hextr. Ascorbic acid was not found either in Hextr or in Lextr. Upon extract combination (1:1, v/v), the FRAP assay revealed additive action between Lextr and Hextr, whilst a slight synergistic action was observed in TAA as measured by the TEAC assay. Synergistic action was better revealed when TAA was analysed using either U937 or HepG2 cells. This could be explained by the presence of a multiphase media (cell membrane and extra- and intracellular media) that might facilitate the distribution and interaction of antioxidants with different polarities and different mechanisms of action.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Martinez, L. Cabrera, M. Navarrete, J. Garcia, P. Gonzalez, A. Ramirez, and U. Martinez

Abstract  

Gamma exposure rate and radon levels were measured in 75 single-family dwellings in Mexico City in order to correlate them with local environment. Radon monitoring was performed both indoors and outdoors using a continuous working level monitor for short-lived radon decay products; the gamma exposure rate was measured using CaSO4: Dy+PTFE. The results obtained show a log-normal distribution. The mean indoor radon concentration is lower than 45 Bq/m3 and the mean indoor gamma exposure rate was 11.29 R/h.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: G. Ferro-Flores, L. García-Salinas, M. Pedraza-López, M. González-Zavala, J. Tendilla, and M. López-Gómez

Abstract  

A new type of preparation employing153Sm metallic-hydroxide macroaggregates (153Sm-MHM) for radiation synovectomy was developed. The radiopharmaceutical was prepared by reacting the aqueous solution of153SmCl3 with sodium borohydride solution in 0.5N NaOH. Microscopic analysis showed that153Sm-MHM mean particle size was 4 m (range 1–15 m) avoiding the formation of fine particles (<1 m) which were153Sm-hydroxide macroaggregates preparations (153Sm-HM). Also, suspension properties as sedimentation rate, were better for153Sm-MHM than for153Sm-hydroxyapatite and153Sm-HM. Biological studies in normal rabbits demonstrated high retention into de Knee joint space even at 48 h after administration of153Sm-MHM (>99%).

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Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Ramírez-García, M. Jiménez-Reyes, M. Solache-Ríos, E. Fernández-Ramírez, H. López-González, and A. Rojas-Hernández

Abstract  

The solubility of europium at 0.02M, 0.1M and 0.7M NaClO4 ionic strength solutions was determined by a radiometric method and pEus-pCH diagrams were obtained. Hydrolysis constants were also determined at the same ionic strengths by pH titration and the values found were log * 1 = -7.68±0.11, -8.07±0.10 and -8.20±0.11. The log K sp values were -23.5±0.2, -22.7±0.2 and -21.9±0.2 for 0.02M, 0.1M and 0.7M NaClO4 ionic strengths, respectively, at 303 K under CO2-free conditions and the extrapolated value at zero ionic strength was log K sp 0 = -24.15. The working pCH ranges for the calculation of the hydrolysis constants were selected from the pEus-pCH diagrams in the region where precipitation of europium oxide or hydroxide was less than 20%. Europium removal from aqueous solutions with zeolites was explored.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: P. Lam Ramos, D. Frías Fonseca, M. González Garcia, D. Aguiar Lambert, J. Estévez Alvarez, I. Pupo González, and D. López Sánchez

Abstract  

The objective of the present study was the elaboration of a procedure for the determination of Y, La, Ce, Pr and Nd in soils by spectrophotometry with Arsenazo III preceded by a separation-concentration stage, which includes coprecipitation and ion exchange. Multielement analysis by energy dispersive X-ray fluorescence (including Y, La, Ce and Nd) and flame atomic absorption spectrophotometry was carried out simultaneously in order to obtain a general characterization of the soil samples. Certified reference materials and statistical intercomparison of the obtained results were used to evaluate the accuracy of the methods. The precision was examined by analyzing replicate samples.

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