A new method based on selective fluorescent polymers (PSresin) for the analysis of 90Sr in presence of 210Pb in environmental samples.

90Sr is of major concern in emergency and environmental control plans. It is one of the main fission products in nuclear facilities and is a high-energy beta emitter that presents chemical properties similar to those of calcium. 90Sr is commonly detected using methods based on liquid scintillation counting (LSC) following a chemical separation to remove potential interferences. However, these methods generate mixed wastes (hazardous and radioactive). In recent years, an alternative strategy using PSresins has been developed. For 90Sr analysis with PSresins, 210Pb is the main interferent that should be considered, as it is also strongly retained in the PSresin. In this study, a procedure was developed involving a precipitation with iodates to separate lead from strontium before the PSresin separation. Moreover, the method developed was compared with well-established and routinely used methods based on LSC, revealing that the new method produced equivalent results in less time and with less waste generation.

A rapid method for 90Sr determination in the presence of 137Cs in environmental samples.

A rapid method for the determination of 90Sr in the presence of 137Cs using the Cherenkov radiation technique is described. The contribution of 137Cs to gross Cherenkov radiation (90Y + 137Cs) was examined for 137Cs /90Sr ratios ranging from 0.09 to 2.50 for 137Cs activities ranging from 2 to 1,211 Bq. Results from direct Cherenkov radiation measurement and results after radiochemical separation of 90Y from 90Sr for samples containing both 90Sr and 137Cs were compared. Errors below 5% were obtained for 137Cs /90Sr ratios lower than 1, when no separation was performed, independently of the activity level. However, errors between 10% and 35% were obtained for 137Cs/90Sr ratios higher than 1. In order to determine 90Sr activity in the presence of 137Cs using the Cherenkov technique, a multiple linear regression analysis model was established to correct the data for 137Cs content. The mathematical correction proposed was validated using 66 artificially contaminated lettuce samples in a laboratory experiment by taking into account the activity levels of 137Cs and 90Sr and the radionuclide ratios. Comparison of mathematically corrected radionuclide ratios with the results obtained without correction shows that, for radionuclide ratios higher than 1, error values for measuring 90Sr activity using the mathematical model were much smaller than when no radiochemical separation was performed. On the other hand, for ratios lower than 1, error values when measuring 90Sr activity with radiochemical separation were smaller than when mathematical correction was performed. In spite of this, the mathematical correction is an appropriate way of reducing the time needed to determine radiostrontium using the Cherenkov radiation technique. The method proposed could be a powerful tool for environmental research whenever the contents of 90Sr and 137Cs have to be determined.

Simultaneous determination of gross alpha, gross beta and ²²6Ra in natural water by liquid scintillation counting.

The determination of gross alpha, gross beta and (226)Ra activity in natural waters is useful in a wide range of environmental studies. Furthermore, gross alpha and gross beta parameters are included in international legislation on the quality of drinking water [Council Directive 98/83/EC]. In this work, a low-background liquid scintillation counter (Wallac, Quantulus 1220) was used to simultaneously determine gross alpha, gross beta and (226)Ra activity in natural water samples. Sample preparation involved evaporation to remove (222)Rn and its short-lived decay daughters. The evaporation process concentrated the sample ten-fold. Afterwards, a sample aliquot of 8 mL was mixed with 12 mL of Ultima Gold AB scintillation cocktail in low-diffusion vials. In this study, a theoretical mathematical model based on secular equilibrium conditions between (226)Ra and its short-lived decay daughters is presented. The proposed model makes it possible to determine (226)Ra activity from two measurements. These measurements also allow determining gross alpha and gross beta simultaneously. To validate the proposed model, spiked samples with different activity levels for each parameter were analysed. Additionally, to evaluate the model's applicability in natural water, eight natural water samples from different parts of Spain were analysed. The eight natural water samples were also characterised by alpha spectrometry for the naturally occurring isotopes of uranium ((234)U, (235)U and (238)U), radium ((224)Ra and (226)Ra), (210)Po and (232)Th. The results for gross alpha and (226)Ra activity were compared with alpha spectrometry characterization, and an acceptable concordance was obtained.

A comparative experimental study of gross alpha methods in natural waters.

The aim of the present work was to compare the results obtained with gross alpha methods such as evaporation, co-precipitation and total evaporation by liquid scintillation counting and to check whether these results are representative of the real total alpha activity concentration on the sample. The study was carried out on eight natural waters with very different radioactive characteristics. For all the samples uranium ((238)U, (235)U, and (234)U), radium ((226)Ra and (224)Ra), (210)Po, and (232)Th isotopes were also assayed by using radiochemical separation and alpha spectrometry in order to determine the sum of the activities of these alpha emitters. Precision (expressed as relative standard deviation) was below 28% for evaporation and below 18% for co-precipitation. In the case of total by liquid scintillation counting it was below 10% for samples with Total Alpha activity above 0.1 Bq/L (this value is about three times the MDA). Furthermore, for most of the studied waters, the Total Alpha activity and the gross alpha activity determined by the three methods were comparable. The obtained bias by the evaporation, co-precipitation, and total evaporation by liquid scintillation counting methods was lower than 40%, 25% and 20%, respectively. The ANOVA test was applied to find out if there was significant variability among the methods. For the samples with the most common radiochemical characteristics there were no significant differences among the three studied methods. However differences were detected for samples with a high saline content or with a very low activity level.

[Cardiovascular manifestations of eosinophilia: clinical and echocardiographic presentation]. / Atteintes cardiaques au cours des hyperéosinophilies: une présentation clinique et échocardiographique polymorphe.

INTRODUCTION: Endomyocardial fibrosis with apical obliteration is the best known involvement among heart lesions induced by hypereosinophilia. However, hypereosinophilic heart disease may involve all three heart layers, with a polymorphic clinical and echocardiographic presentation. METHODS: Retrospective descriptive study of five patients highlighting the various manifestations of hypereosinophilic heart disease. RESULTS: We report five cases illustrating the variety of hypereosinophilic heart disease and review the pathophysiology of this potentially severe illness: cytotoxicity of eosinophils is mediated by the release of granular proteins that primarily damage the endocardium, leading to thrombosis and embolic complications, then to fibrosis and valvular complications; myocardial involvement may induce a dreadful acute eosinophilic myocarditis; finally, pericardial involvement may cause tamponade. CONCLUSION: These observations highlight the whole spectrum of the heart manifestations of hypereosinophilia, remind that the vital prognosis may be involved in the acute phase and underline that functional prognosis depends on early detection and treatment to reduce the risk of early thromboembolic and late fibrotic complications.