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  • Author or Editor: H. Papaefthymiou x
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Abstract  

The oscillatory isothermal behaviour of three cobalt(III) compounds, trans- and cis[Co(en)2Cl2]NO3 and [Co(en)3] (NO3)3, irradiated by neutrons in the crystalline state, appears to be different depending on structural and electrostatic parameters. The temperature coefficient of frequency in the trans and cis compounds is negative, while that of the amplitude is positive. Both temperature coefficients are the opposite in case of the trisethylenediamine compound. The oscillatory isotope exchange, responsible for these phenomena, is mechanistically approached by applying a modified Lotka-Volterra model to the radiation damaged state in the frame of non-equilibrium thermodynamics.

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Abstract  

Bulk deposition samples were collected on a monthly basis in Megalopolis city, located near lignite power plants. A total of 23 elements (As, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Mo, Na, Rb, Sb, Sc, Se, Ta, Tb, Th, U, Yb, Zn) were detected in the collected samples using INAA. The coal burning marker elements As and Se were found enriched in the collected samples together with Mo, Br, Sb, U and Zn. Factor analysis permitted the identification of four sources: re-suspended soil/road dust, lignite power plant, sea spray and traffic emissions. A wind direction effect on deposition rates of all elements (except rates of Na, Rb, Sb and Zn) was also found.

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Abstract  

In this study, instrumental neutron activation analysis (INAA) and inductively coupled plasma-mass spectrometry (ICP-MS) were used to compare results obtained by both techniques for sediment samples collected from the Patras Harbour, Western Greece. The accuracy of the methods was tested using reference materials. In total seven elements were measured by both techniques (Zn, Ni, Cr, Ba, As, U, Co). Results obtained by ICP-MS were compared with those obtained by INAA by applying paired t-test. Insignificant differences in mean concentration values were found for Zn, Ni, Cr and Ba, whereas the differences for As, Co and U were significant. Correlations between element concentrations measured by both techniques are also discussed.

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Summary  

Bulk deposition samples were collected simultaneously, on a monthly basis, in two cities differing in pollution sources in southern Greece (Patras and Megalopolis) during February 1997 - January 1998. Megalopolis is situated near lignite power plants, while Patras is a typical urban city. Collected samples from three sampling sites in Patras (P1-P3) and five in Megalopolis (M1-M5) were analyzed for major and trace elements using instrumental neutron activation analysis. Comparison of the results illustrated that the deposition rates of most of the analyzed elements, except for Zn, Br, Ca and Sb, were significantly higher in Megalopolis than in Patras, while that of Na was higher in Patras. On the contrary, no differences in monthly dust deposition rates between the two cities were found. A comparison between sampling sites in Patras showed non-significant differences in dust and elemental deposition rates for most of the detected elements, while in Megalopolis the significant effect for dust and most elements was attributed to the higher deposition rates of site M5, located in the power plant A area.

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Abstract  

The oscillatory phenomenon during isothermal annealing of neutron irradiated crystalline cobaltic complexes is shown to extend for heating times up to 120 h without significant damping of amplitude and frequency of the oscillations. A mechanistic approach based on the Volterra-Lotka model is attempted involving defects and dissipative structure according to non-equilibrium thermodynamics.

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Abstract  

Activity concentration measurements of natural radionuclides performed by γ-ray spectrometry and ICP-MS in sediment samples from the Gulf of Itea and in surface soil samples collected from the surrounding area of a bauxite beneficiation plant, showed that (1) the breaker zone of the Itea Gulf, in the vicinity of the bauxite beneficiation plant, is contaminated with 238U, 232Th and 226Ra, (2) the activities in sediment samples from the rest of the Gulf were at the background level, and (3) enhanced activities of the 238U, 232Th and 226Ra were found in a number of soil samples due to bauxite dust deposition from the nearby beneficiation plant. The application of the optimized BCR sequential extraction procedure on the surface sediment samples showed that the U and Th were strongly bound to the sediments.

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Abstract  

Elemental concentrations and specific activity values of natural radionuclides were measured in lignite, bottom ash and fly ash samples collected from the Megalopolis power plant A in southern Greece, using nuclear analytical techniques. The results show that the elements As, Br, Mo, Sb, Se, and U were enriched in the lignite samples, the elements Mo, Se and U in bottom ash, while fly ash samples were enriched in As, Mo, Sb, Se and U. Specific activity measurements also show that 238U (226Ra) activity values in lignite and both ash samples were high relative to the corresponding data for coal and earth crust given in the literature. As a high quantity of fly ash is produced during the operation of the lignite power plant A, this power plant should be considered as a major source of air particulate pollution and radiation to the population living in the vicinity of lignite burning power plant.

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Summary  

The nutrient trace elements chromium, iron and zinc as well as cobalt, rubidium and scandium were determined in dry spaghetti sauce samples from the Greek market by instrumental neutron activation analysis. The results were evaluated according to the new US Recommended Dietary Allowances (RDA), US Adequate Intake (AI), US Reference Values for nutrition labeling (RVNL) and European Union reference values for nutrition labeling (EURV). Moreover, the same data has been used with pattern recognition techniques in order to classify the sauce samples according to their labeled flavor. The evaluation showed that the nutrition rate depends strongly on the reference value under consideration. The spaghetti sauces studied are a good source for the covering of chromium daily AI. The same sauces are poor source for zinc daily needs of the organism (RDA, RVNL), but they are a moderate source for iron daily needs (RDA). The application of cluster analysis, of linear discriminant analysis and of the principal component analysis classified the spaghetti sauce samples according to their labeled taste successfully. In addition using the same techniques, another classification in red and white spaghetti sauces is carried out according to their tomato content.

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Abstract  

In continuation, of an early study of trace metal /TM/ccontent of Greek lignites and power plant ashes, taken to assess mobilization of TM in Greece by the operation of power plants, new data are presented. Both power plant sites in Greece, i. e. /a/ Northern /Ptolemais, Kardia/, and /b/ Southern /Megalopolis/ have been examined for trace metal content in ashes and in locally used lignites. Instrumental neutron activation analysis /INAA/ was used to determine the content of about 30 minor and major elements. The uranium content of southern Greek lignites was found again to be exceptionally high. The new data are correlated with those of our previous investigation.

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Summary  

Four different bottled water brands sold in Greece in the winter of 2001-2002 were analyzed for a wide range of chemical elements, using neutron activation analysis (NAA). The elements Na and Br were determined instrumentally (INAA), whereas the other metals and trace elements radiochemically (RNAA). The results indicated that the mean level of all the elements determined in the samples were well within the European Union (EU) directive on drinking water and accomplish the drinking water standards of the World Health Organisation (WHO) as well as of the Food and Drug Administration (FDA).

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