ORCID Profile
0000-0003-0077-0294
Current Organisation
University Hospital of Lausanne
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Publisher: Springer Science and Business Media LLC
Date: 17-06-2009
Publisher: Elsevier BV
Date: 11-2007
Publisher: American Chemical Society (ACS)
Date: 26-04-2016
Abstract: The interaction of trace metals with naturally occurring organic matter (NOM) is a key process of the speciation of trace elements in aquatic environments. The rate of dissociation of metal-NOM complexes will impact the amount of free metal available for biouptake. Assessing the bioavailability of plutonium (Pu) helps to predict its toxic effects on aquatic biota. However, the rate of dissociation of Pu-NOM complexes in natural freshwaters is currently unknown. Here, we used the technique of diffusive gradients in thin films (DGT) with several diffusive layer thicknesses to provide new insights into the dissociation kinetics of Pu-NOM complexes. Results show that Pu complexes with NOM (mainly fulvic acid) are somewhat labile (0.2 ≤ ξ ≤ 0.4), with kd = 7.5 × 10(-3) s(-1). DGT measurements of environmental Pu in organic-rich natural water confirm these findings. In addition, we determined the effective diffusion coefficients of Pu(V) in polyacrylamide (PAM) gel in the presence of humic acid using a diffusion cell (D = 1.70 ± 0.25 × 10(-6) cm(2) s(-1)). These results show that Pu(V) is a more mobile species than Pu(IV).
Publisher: Royal Society of Chemistry (RSC)
Date: 2001
DOI: 10.1039/B107455E
Publisher: Environmental Health Perspectives
Date: 12-2008
DOI: 10.1289/EHP.11358
Publisher: American Chemical Society (ACS)
Date: 07-1993
DOI: 10.1021/IC00067A019
Publisher: American Chemical Society (ACS)
Date: 21-10-2010
DOI: 10.1021/ES101766G
Abstract: Colloidal transport has been shown to enhance the migration of plutonium in groundwater downstream from contaminated sites, but little is known about the adsorption of ⁹⁰Sr and plutonium onto colloids in the soil solution of natural soils. We s led soil solutions using suction cups, and separated colloids using ultrafiltration to determine the distribution of ²³⁹Pu and ⁹⁰Sr between the truly dissolved fraction and the colloidal fraction of the solutions of three Alpine soils contaminated only by global fallout from the nuclear weapon tests. Plutonium was essentially found in the colloidal fraction (>80%) and probably associated with organic matter. A significant amount of colloidal ⁹⁰Sr was detected in organic-rich soil solutions. Our results suggest that binding to organic colloids in the soil solutions plays a key role with respect to the mobility of plutonium in natural alpine soils and, to a lesser extent, to the mobility of ⁹⁰Sr.
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.APRADISO.2012.02.063
Abstract: The work presented here is a new and precise measurement of the half-life of (166m)Ho by determining the activity concentration, using an ionisation chamber calibrated for this nuclide, and measuring the number of (166m)Ho atoms using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Since the isotope (166)Er interferes with the mass spectrometric measurement, Er has to be eliminated from the (166m)Ho radioactive solution. The elimination was achieved using ion-exchange chromatography with the cation exchange resin Dowex AG 50W-X8 and 2-Hydroxybutanoic acid as the mobile phase. After a first transit through the chromatographic column, the purified (166m)Ho eluate was spiked with natural Er to get a resulting Er isotopic composition close to that of natural Er at better than 99.5%, and then it underwent two further separations to eliminate the Er. The activity concentration of this Er-free radioactive (166m)Ho solution was measured in our reference ionisation chamber calibrated for this nuclide by means of the 4πβ(PC)-γ and 4πβ(PS)-4πγ coincidence techniques and integral counting with a well-type NaI(Tl) detector and Monte Carlo efficiencies. An aliquot of this standardized solution was sent to the Paul Scherrer Institute (PSI) for mass concentration determination using an isotope dilution MC-ICP-MS approach. The mass concentration of (166m)Ho in this solution was determined with 0.25% relative standard uncertainty. This value was corroborated by two other independent measurements. The new half-life of (166m)Ho, 1132.6(39) years (k=1), is compatible with the value determined in 1965, but is 5.6% shorter and about 43 times more precise.
Publisher: Elsevier BV
Date: 07-2023
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.FORSCIINT.2012.03.014
Abstract: In forensic science, there is a strong interest in determining the post-mortem interval (PMI) of human skeletal remains up to 50 years after death. Currently, there are no reliable methods to resolve PMI, the determination of which relies almost exclusively on the experience of the investigating expert. Here we measured (90)Sr and (210)Pb ((210)Po) incorporated into bones through a biogenic process as indicators of the time elapsed since death. We hypothesised that the activity of radionuclides incorporated into trabecular bone will more accurately match the activity in the environment and the food chain at the time of death than the activity in cortical bone because of a higher remodelling rate. We found that determining (90)Sr can yield reliable PMI estimates as long as a calibration curve exists for (90)Sr covering the studied area and the last 50 years. We also found that adding the activity of (210)Po, a proxy for naturally occurring (210)Pb incorporated through ingestion, to the (90)Sr dating increases the reliability of the PMI value. Our results also show that trabecular bone is subject to both (90)Sr and (210)Po diagenesis. Accordingly, we used a solubility profile method to determine the biogenic radionuclide only, and we are proposing a new method of bone decontamination to be used prior to (90)Sr and (210)Pb dating.
Publisher: Elsevier BV
Date: 04-2010
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.JENVRAD.2009.01.006
Abstract: The evaluation of radioactivity accidentally released into the atmosphere involves determining the radioactivity levels of rainwater s les. Rainwater scavenges atmospheric airborne radioactivity in such a way that surface contamination can be deduced from rainfall rate and rainwater radioactivity content. For this purpose, rainwater is usually collected in large surface collectors and then measured by gamma-spectrometry after such treatments as evaporation or iron hydroxide precipitation. We found that collectors can be adapted to accept large surface (diameter 47mm) cartridges containing a strongly acidic resin (Dowex AG 88) which is able to quantitatively extract radioactivity from rainwater, even during heavy rainfall. The resin can then be measured by gamma-spectrometry. The detection limit is 0.1Bq per s le of resin (80g) for (137)Cs. Natural (7)Be and (210)Pb can also be measured and the activity ratio of both radionuclides is comparable with those obtained through iron hydroxide precipitation and air filter measurements. Occasionally (22)Na has also been measured above the detection limit. A comparison between the evaporation method and the resin method demonstrated that 2/3 of (7)Be can be lost during the evaporation process. The resin method is simple and highly efficient at extracting radioactivity. Because of these great advantages, we anticipate it could replace former rainwater determination methods. Moreover, it does not necessitate the transportation of large rainwater volumes to the laboratory.
Publisher: American Chemical Society (ACS)
Date: 02-06-2022
Publisher: Elsevier BV
Date: 04-2023
Publisher: Wiley
Date: 29-08-2006
Abstract: Highly selective separation of yttrium (and lanthanides) is of interest for the design of radiopharmaceuticals, and an efficient method based on the ion-imprinting concept is proposed here. The synthesis and structural, thermodynamic and photophysical characterization of complexes of trivalent yttrium and lanthanides with two new vinyl derivatives of dipicolinic acid, HL1 and L2, are described. The feasibility of using ion-imprinted resins for yttrium and lanthanide separation is demonstrated. The resins were obtained by copolymerization with styrene and inylbenzene and subsequent acid treatment to remove the metal ion. High-resolution Eu luminescence experiments revealed that the geometry of the complexation sites is well preserved in the imprinted polymers. The ion-imprinted polymer based on HL1 proved to be particularly well adapted for yttrium extraction, having a sizeable capacity (8.9+/-0.2 mg g(-1) resin) and a fast rate of extraction (t(1/2)=1.7 min). In addition, lighter and heavier lanthanide ions are separated. Finally, the resin displays high selectivity for yttrium and lanthanide cations against alkali and alkaline earth metals. For instance, in a typical experiment, 10 mg of yttrium was extracted from 5 g of milk ash s le by 2 g of the resin. The good separation properties displayed by the resin based on HL1 open interesting perspectives for the production of highly pure (90)Y and radiolanthanides for medical applications, and for trace analysis of these radiochemicals in food and in the environment.
Publisher: Elsevier BV
Date: 15-07-2010
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.FORSCIINT.2015.09.019
Abstract: The late president of the Palestinian Authority, Yasser Arafat, died in November 2004 in Percy Hospital, one month after having experienced a sudden onset of symptoms that included severe nausea, vomiting, diarrhoea and abdominal pain and which were followed by multiple organ failure. In spite of numerous investigations performed in France, the pathophysiological mechanisms at the origin of the symptoms could not be identified. In 2011, we found abnormal levels of polonium-210 ((210)Po) in some of Arafat's belongings that were worn during his final hospital stay and which were stained with biological fluids. This finding led to the exhumation of Arafat's remains in 2012. Significantly higher (up to 20 times) activities of (210)Po and lead-210 ((210)Pb) were found in the ribs, iliac crest and sternum specimens compared to reference s les from the literature (p-value <1%). In all specimens from the tomb, (210)Po activity was supported by a similar activity of (210)Pb. Biokinetic calculations demonstrated that a (210)Pb impurity, as identified in a commercial source of 3MBq of (210)Po, may be responsible for the activities measured in Arafat's belongings and remains 8 years after his death. The absence of myelosuppression and hair loss in Mr Arafat's case compared to Mr Litvinenko's, the only known case of malicious poisoning with (210)Po, could be explained by differences in the time delivery-scheme of intake. In conclusion, statistical Bayesian analysis combining all the evidence gathered in our forensic expert report moderately supports the proposition that Mr Arafat was poisoned by (210)Po.
Publisher: Elsevier BV
Date: 09-2003
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.JHAZMAT.2011.09.037
Abstract: Since 1998 the highly polluted Havana Bay ecosystem has been the subject of a mitigation program. In order to determine whether pollution-reduction strategies were effective, we have evaluated the historical trends of pollution recorded in sediments of the Bay. A sediment core was dated radiometrically using natural and artificial fallout radionuclides. An irregularity in the (210)Pb record was caused by an episode of accelerated sedimentation. This episode was dated to occur in 1982, a year coincident with the heaviest rains reported in Havana over the XX century. Peaks of mass accumulation rates (MAR) were associated with hurricanes and intensive rains. In the past 60 years, these maxima are related to strong El Niño periods, which are known to increase rainfall in the north Caribbean region. We observed a steady increase of pollution (mainly Pb, Zn, Sn, and Hg) since the beginning of the century to the mid 90 s, with enrichment factors as high as 6. MAR and pollution decreased rapidly after the mid 90 s, although some trace metal levels remain high. This reduction was due to the integrated coastal zone management program introduced in the late 90 s, which dismissed catchment erosion and pollution.
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.WATRES.2022.118838
Abstract: Nuclear discharges to the oceans have given rise to significant accumulations of radionuclides in sediments which can later remobilise back into the water column. A continuing supply of radionuclides to aquatic organisms and the human food chain can therefore exist, despite the absence of ongoing nuclear discharges. Radionuclide remobilisation from sediment is consequently a critical component of the modelled radiation dose to the public. However, radionuclide remobilisation fluxes from contaminated marine sediments have never been quantitatively determined in-situ to provide a valid assessment of the issue. Here, we combine recent advances in the Diffusive Gradients in Thin Films (DGT) s ling technique with ultrasensitive measurement by accelerator mass spectrometry (AMS) to calculate the remobilisation fluxes of plutonium, americium and uranium isotopes from the Esk Estuary sediments (UK), which have accumulated historic discharges from the Sellafield nuclear reprocessing facility. Isotopic evidence indicates the local biota are accumulating remobilised plutonium and demonstrates the DGT technique as a valid bioavailability proxy, which more accurately reflects the elemental fractionation of the actinides in the biota than traditional bulk water s ling. These results provide a fundamental evaluation of the re-incorporation of bioavailable actinides into the biosphere from sediment reservoirs. We therefore anticipate this work will provide a tool and point of reference to improve radiation dose modelling and contribute insight for other environmental projects, such as the near-surface and deep disposal of nuclear waste.
Publisher: Springer Science and Business Media LLC
Date: 20-06-2022
DOI: 10.1038/S41598-022-14200-2
Abstract: 210 Po is a radioactive component of conventional cigarette tobacco smoke and is a recognized carcinogen. Despite the expanding market of heated tobacco products, no data are available on the activity of 210 Po in the smoke of IQOS Heets cigarette. We determined the 210 Po activity in the mainstream smoke of thirteen cigarette brands available on the Swiss market using a smoking machine and compared the results to the 210 Po activity measured in the mainstream smoke of the IQOS system. In addition, we measured the 210 Po and 210 Pb loss on heating after uniform heating from 50 to 600 °C for several cigarette brands and the Heets cigarettes. 13.6 ± 4.1% of 210 Po activity was found in the mainstream smoke in conventional cigarette smoking (7% for 210 Pb). This dropped to 1.8 ± 0.3% in the mainstream smoke of IQOS Heets. Conversely, when the tobacco was heated uniformly at 330 °C, a loss of 210 Po of more than 80% was observed for all type of cigarettes. Apparently, IQOS significantly reduced the 210 Po and 210 Pb activities in the mainstream smoke. However, our results show that only 15% of the Heets tobacco reaches 330 °C with IQOS. While IQOS reduces the 210 Po and 210 Pb activities in the mainstream smoke compared to conventional cigarettes, it only heats a marginal fraction of the tobacco present in the Heets cigarette. Because smoking is an addiction (mostly due to nicotine), IQOS could possibly deliver an unsatisfactory dose of nicotine to a Heets cigarette smoker, as most of the tobacco is left unaltered.
Publisher: American Chemical Society (ACS)
Date: 18-08-2000
DOI: 10.1021/ES9913636
Publisher: American Chemical Society (ACS)
Date: 04-1995
DOI: 10.1021/IC00112A019
Publisher: American Chemical Society (ACS)
Date: 27-08-2014
DOI: 10.1021/ES501149V
Abstract: The toxicity of heavy metals in natural waters is strongly dependent on the local chemical environment. Assessing the bioavailability of radionuclides predicts the toxic effects to aquatic biota. The technique of diffusive gradients in thin films (DGT) is largely exploited for bioavailability measurements of trace metals in waters. However, it has not been applied for plutonium speciation measurements yet. This study investigates the use of DGT technique for plutonium bioavailability measurements in chemically different environments. We used a diffusion cell to determine the diffusion coefficients (D) of plutonium in polyacrylamide (PAM) gel and found D in the range of 2.06-2.29 × 10(-6) cm(2) s(-1). It ranged between 1.10 and 2.03 × 10(-6) cm(2) s(-1) in the presence of fulvic acid and in natural waters with low DOM. In the presence of 20 ppm of humic acid of an organic-rich soil, plutonium diffusion was hindered by a factor of 5, with a diffusion coefficient of 0.50 × 10(-6) cm(2) s(-1). We also tested commercially available DGT devices with Chelex resin for plutonium bioavailability measurements in laboratory conditions and the diffusion coefficients agreed with those from the diffusion cell experiments. These findings show that the DGT methodology can be used to investigate the bioaccumulation of the labile plutonium fraction in aquatic biota.
Publisher: American Chemical Society (ACS)
Date: 26-09-2000
DOI: 10.1021/IC000353Z
Abstract: The reactions of various derivatives of chelidamic acid (4-hydroxypyridine-2,6-dicarboxylic acid) with p-tert-butylcalix[4]arene have produced several new mono- and difunctionalized derivatives of the calixarene in which tridentate functional groups suitable for the binding of rare earth metal cations have been incorporated. Single-crystal X-ray structure determinations have been performed on two difunctionalized calixarenes found to adopt different "cone" and "1,2-alternate" conformations, as well as on a complex of europium(III) with the phenoxide form of a monofunctionalized ligand, this structure confirming that charge factors are dominant in determining the site of lanthanide metal binding in these ligands.
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 08-2007
Publisher: American Chemical Society (ACS)
Date: 09-1990
DOI: 10.1021/IC00344A044
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.APRADISO.2008.02.032
Abstract: As part of a project to use the long-lived (T(1/2)=1200a) (166m)Ho as reference source in its reference ionisation chamber, IRA standardised a commercially acquired solution of this nuclide using the 4pibeta-gamma coincidence and 4pigamma (NaI) methods. The (166m)Ho solution supplied by Isotope Product Laboratories was measured to have about 5% Europium impurities (3% (154)Eu, 0.94% (152)Eu and 0.9% (155)Eu). Holmium had therefore to be separated from europium, and this was carried out by means of ion-exchange chromatography. The holmium fractions were collected without europium contamination: 162h long HPGe gamma measurements indicated no europium impurity (detection limits of 0.01% for (152)Eu and (154)Eu, and 0.03% for (155)Eu). The primary measurement of the purified (166m)Ho solution with the 4pi (PC) beta-gamma coincidence technique was carried out at three gamma energy settings: a window around the 184.4keV peak and gamma thresholds at 121.8 and 637.3keV. The results show very good self-consistency, and the activity concentration of the solution was evaluated to be 45.640+/-0.098kBq/g (0.21% with k=1). The activity concentration of this solution was also measured by integral counting with a well-type 5''x5'' NaI(Tl) detector and efficiencies computed by Monte Carlo simulations using the GEANT code. These measurements were mutually consistent, while the resulting weighted average of the 4pi NaI(Tl) method was found to agree within 0.15% with the result of the 4pibeta-gamma coincidence technique. An oule of this solution and the measured value of the concentration were submitted to the BIPM as a contribution to the Système International de Référence.
Publisher: Elsevier BV
Date: 08-2014
Publisher: Springer Science and Business Media LLC
Date: 04-02-2012
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.FORSCIINT.2013.10.038
Abstract: In legal medicine, the post mortem interval (PMI) of interest covers the last 50 years. When only human skeletal remains are found, determining the PMI currently relies mostly on the experience of the forensic anthropologist, with few techniques available to help. Recently, several radiometric methods have been proposed to reveal PMI. For instance, (14)C and (90)Sr bomb pulse dating covers the last 60 years and give reliable PMI when teeth or bones are available. (232)Th series dating has also been proposed but requires a large amount of bones. In addition, (210)Pb dating is promising but is submitted to diagenesis and in idual habits like smoking that must be handled carefully. Here we determine PMI on 29 cases of forensic interest using (90)Sr bomb pulse. In 12 cases, (210)Pb dating was added to narrow the PMI interval. In addition, anthropological investigations were carried out on 15 cases to confront anthropological expertise to the radiometric method. Results show that 10 of the 29 cases can be discarded as having no forensic interest (PMI>50 years) based only on the (90)Sr bomb pulse dating. For 10 other cases, the additional (210)Pb dating restricts the PMI uncertainty to a few years. In 15 cases, anthropological investigations corroborate the radiometric PMI. This study also shows that diagenesis and inter-in idual difference in radionuclide uptake represent the main sources of uncertainty in the PMI determination using radiometric methods.
Publisher: MyJove Corporation
Date: 18-09-2510
DOI: 10.3791/53188
Publisher: Walter de Gruyter GmbH
Date: 13-01-2011
Abstract: A procedure was developed for determining 241 Pu activity in environmental s les. This beta emitter isotope of plutonium was measured by ultra low level liquid scintillation, after several separation and purification steps that involved the use of a highly selective extraction chromatographic resin (Eichrom-TEVA). Due to the lack of reference material for 241 Pu, the method was nevertheless validated using four IAEA reference sediments with information values for 241 Pu. Next, the method was used to determine the 241 Pu activity in alpine soils of Switzerland and France. The 241 Pu/ 239,240 Pu and 238 Pu/ 239,240 Pu activity ratios confirmed that Pu contamination in the tested alpine soils originated mainly from global fallout from nuclear weapon tests conducted in the fifties and sixties. Estimation of the date of the contamination, using the 241 Pu/ 241 Am age-dating method, further confirmed this origin. However, the 241 Pu/ 241 Am dating method was limited to s les where Pu-Am fractionation was insignificant. If any, the contribution of the Chernobyl accident is negligible.
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.ACA.2021.339421
Abstract: Actinium-225 is a highly radiotoxic alpha-emitting radionuclide, which is currently in the spotlight owing to its promising radiotherapeutic applications in nuclear medicine. Personnel involved in the production and handling of actinium-225 is exposed to a risk of accidental incorporation of this radionuclide. Radiological protection regulations require regular monitoring of incorporation and internal dosimetry assessment for workers manipulating open radioactive sources. Urine is often used as a biological s le for measuring the incorporation of actinides, however it requires a radiochemical separation with a certified metrological tracer to enable quantitative determination. There is no stable, nor sufficiently long-lived radioactive isotopes of actinium to provide a metrological yield tracer. In this article, we propose an application of an ion-imprinted polymer resin to extract actinium-225 from urine employing americium-243 as a radioactive tracer. The radiochemical separation was followed by a quantitative determination with alpha-spectrometry. Solid-phase extraction of both actinides from urine using ion-imprinted polymer resin resulted in good radiochemical yields: 57.7 ± 16.5% (n = 17) for actinium-225 and 62.8 ± 18.0% (n = 17) for americium-243. Equivalent recoveries showed that americium-243 is a suitable yield tracer for the determination of actinium-225 with an ion-imprinted polymer resin. Combined with a different measurement technique, this method can be applied for the separation of other isotopes of actinium, such as actinium-227.
Publisher: Elsevier BV
Date: 2004
Publisher: Springer Science and Business Media LLC
Date: 2004
Publisher: American Chemical Society (ACS)
Date: 26-10-2010
DOI: 10.1021/ES100954H
Abstract: Mountainous areas are often covered by little evolved soils from which deposited radionuclides can potentially leak into the vadose zone. In the Swiss Jura mountains, we observed unusual isotopic ratios of nuclear weapon test (NWTs) fallout with an apparent loss of NWTs plutonium relative to ¹³⁷Cs of Chernobyl origin in thinner soils. Here, we studied the karstic watershed of a vauclusian spring to determine the residence times of plutonium, ²⁴¹Am, and ⁹⁰Sr deposited by global fallout and their respective mobility in carbonaceous soils. The results show that ⁹⁰Sr is washed most efficiently from the watershed with a residence time of several hundred years. The estimated plutonium residence time is more than 10 times higher (in the range of 5000-10,000 years), and the ²⁴¹Am residence time is double that of plutonium. The spring water ²⁴¹Am/²³⁹+²⁴⁰Pu isotopic ratio is lower (0.12 - 0.28) than found in watershed soils (0.382 ± 0.077). Similar differences are found in aquatic mosses (²⁴¹Am/²³⁹+²⁴⁰Pu isotopic ratio 0.05-0.12), which are permanently submerged in spring waters. In contrast to plutonium, ⁹⁰Sr is leached from these mosses with 0.5M HCl, demonstrating that strontium is probably associated with calcium carbonate precipitations on the mosses. The higher plutonium to americium isotopic ratio found in the s les of spring water and mosses at the outlet of the karst shows that plutonium mobility is enhanced.
Publisher: Wiley
Date: 30-01-1991
Publisher: Elsevier BV
Date: 02-2011
Publisher: Elsevier BV
Date: 07-2020
Publisher: Elsevier BV
Date: 10-2013
Publisher: Swiss Chemical Society
Date: 23-12-2020
Abstract: Natural radionuclides are ubiquitous in the environment. In addition, artificial radionuclides are present in the Swiss environment after the fallout of the nuclear bomb tests of the 1950s and 1960s, after the accident of the Chernobyl nuclear power plant, or after authorized discharges from the Swiss nuclear power plants and research centres. These radionuclides can create a radiological hazard to the environment and humans because of the increased risk of cancer due to the ionizing radiation they produce. Here we show that some of these radionuclides have made their way from the air or the soil to the human body, where they target mostly the skeleton. However, the activity levels of 90 Sr, 239 Pu and 240 Pu, 226 Ra and 210 Pb/ 210 Po found in the human body remain very low and do not represent a public health issue at the current body burden.
Publisher: Springer Science and Business Media LLC
Date: 18-09-2021
DOI: 10.1007/S10967-021-07974-8
Abstract: In 90 Sr analysis, determining its daughter 90 Y improves the sensitivity of the radiometric methods. We found that to imprint a cavity made of [Y(6-(4-Vinylphenylcarbamoyl)pyridine-2-carboxylate) 3 ] into a polystyrene skeleton yields a solid phase extraction resin with high selectivity for Y and Ln(III) over transition metals, alkaline, and alkaline-earth cations. We used this resin in an automated chromatography system to extract 90 Y from milk, grass, vegetables, soil, sediments, water, human bones, and milk teeth s les. We found that the ion-imprinted resin could be used to separate light Ln(III) using a pH gradient, favoring the targeting of molecules used in nuclear medicine.
Publisher: Royal Society of Chemistry (RSC)
Date: 1995
DOI: 10.1039/DT9950000083
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.CHEMOSPHERE.2010.04.049
Abstract: Plutonium and (90)Sr are considered to be among the most radiotoxic nuclides produced by the nuclear fission process. In spite of numerous studies on mammals and humans there is still no general agreement on the retention half time of both radionuclides in the skeleton in the general population. Here we determined plutonium and (90)Sr in human vertebrae in in iduals deceased between 1960 and 2004 in Switzerland. Plutonium was measured by sensitive SF-ICP-MS techniques and (90)Sr by radiometric methods. We compared our results to the ones obtained for other environmental compartments to reveal the retention half time of NBT fallout (239)Pu and (90)Sr in trabecular bones of the Swiss population. Results show that plutonium has a retention half time of 40+/-14 years. In contrast (90)Sr has a shorter retention half time of 13.5+/-1.0 years. Moreover (90)Sr retention half time in vertebrae is shown to be linked to the retention half time in food and other environmental compartments. These findings demonstrate that the renewal of the vertebrae through calcium homeostatic control is faster for (90)Sr excretion than for plutonium excretion. The precise determination of the retention half time of plutonium in the skeleton will improve the biokinetic model of plutonium metabolism in humans.
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 08-2006
DOI: 10.1016/J.SCITOTENV.2006.02.011
Abstract: Switzerland has recorded the level of activity of 90Sr in the milk teeth of children from different regions of the country since the first atomic explosions in the atmosphere. Activity peaked at 0.421 Bq g-1 Ca at the beginning of the sixties, coinciding with the detonation of many large nuclear devices. Following the Nuclear Test Ban Treaty that ended atmospheric nuclear weapon tests, a steady and significant decrease in 90Sr activity in milk teeth has been observed-down to a value of 0.03 Bq g-1 Ca for children born in 1994. The apparent half-life of 90Sr in milk teeth is 9.8+/-3 years. With the exception of the period from 1962 to 1964, there is no correlation between the activity in the teeth of children born in a given year and the year of extraction. Between 1953 and 1992, the milk teeth of children born in Zürich county showed 16% less activity than teeth from children born in Vaud county. Dairy consumption habits might be responsible for this trend. The effect of the 90Sr deposition from Chernobyl is barely measurable in milk teeth, and no effect is seen from the five Swiss nuclear reactors. This paper emphasizes the necessity of a very high purity chemical separation of 90Sr or 90Y to determine 90Sr activity in milk teeth or other s les.
Publisher: Swiss Chemical Society
Date: 28-04-2006
DOI: 10.2533/000942906777674895
Abstract: The metal ion imprinted concept has been used to imprint dipicolinic derivative coordination cages in styrene-based polymeric material. This resin displays very high selectivity for yttrium and lanthanides. Distribution coefficients determined for 88Y and 85Sr emphasize the possibility for the material to be used as chromatographic support for direct production of medical grade 90Y from a 90Sr source. Europium has been successfully extracted by the resin from a large volume of tap water. Thus the material could be used for radiation monitoring of nuclear power plants, particularly regarding the determination of radiolanthanides in the cooling system.
Publisher: American Chemical Society (ACS)
Date: 09-2022
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.CHEMOSPHERE.2006.08.008
Abstract: Contamination of the environment by radionuclides is usually estimated using soil and grass s ling. However, radionuclides are often not homogeneously distributed in soils. In the alpine Mercantour region (Western Alps, France) a large heterogeneity in Chernobyl 137Cs deposition has been previously observed. Here we report additional 137Cs results together with new 90Sr and Pu data for soil, grass, milk, and cheese s les. The results show that radioisotopes from nuclear weapons tests fallout are more homogeneously distributed than Chernobyl 137Cs. Further, we observe that the 137Cs and 90Sr contents are less variable in milk s les than in grass or soil s les. This can be attributed to the homogenization effect of cow vagrancy during grazing. Hence milk seems to be a more robust s le than soil or grass to evaluate the extent of contamination on a regional scale. We explore this idea by comparing own unpublished 90Sr results and 90Sr results from the literature to establish the relationship between altitude of grazing and contamination of soil and milk for Western Europe. There is a significant positive correlation between soil contamination and altitude and an even closer correlation between milk 90Sr activity (A) and altitude (h): A = A0 + e(k x h) where A0 is the expected activity of milk s led at sea level (A0 = 0.064 +/- 0.014 Bq g(-1) Ca) and h is the altitude of grazing, k being a constant (k = 0.95 x 10(-3) +/- 0.11 x 10(-3) m(-1) Bq g(-1) Ca). The fact that there is less scattering in the relationship for the 90Sr(milk)-altitude than for 90Sr(soil)-altitude suggests, again, that milk is a well-suited s le for environmental survey. The relationship between the altitude of grazing and the 90Sr content of milk and cheese can also be used to assess the authenticity of dairy products.
Publisher: Springer Science and Business Media LLC
Date: 07-01-2014
DOI: 10.1038/NCOMMS4030
Abstract: The atmospheric nuclear testing in the 1950s and early 1960s and the burn-up of the SNAP-9A satellite led to large injections of radionuclides into the stratosphere. It is generally accepted that current levels of plutonium and caesium radionuclides in the stratosphere are negligible. Here we show that those radionuclides are present in the stratosphere at higher levels than in the troposphere. The lower content in the troposphere reveals that dry and wet deposition efficiently removes radionuclides within a period of a few weeks to months. Since the stratosphere is thermally stratified and separated from the troposphere by the tropopause, radioactive aerosols remain longer. We estimate a mean residence time for plutonium and caesium radionuclides in the stratosphere of 2.5-5 years. Our results also reveal that strong volcanic eruptions like Eyjafjallajökull in 2010 have an important role in redistributing anthropogenic radionuclides from the stratosphere to the troposphere.
Publisher: Elsevier BV
Date: 06-2017
Publisher: American Chemical Society (ACS)
Date: 25-08-2021
Publisher: Proceedings of the National Academy of Sciences
Date: 16-05-2019
Abstract: Ultra-high dose-rate (≥100 Gy⋅s −1 ) irradiation, termed FLASH radiotherapy, affords some remarkable (if not unexpected) normal tissue sparing in the irradiated brain when compared with conventional dose rates (0.07–0.1 Gy⋅s −1 ) used in clinical practice. Radiation-induced neurocognitive deficits, persistent neuroinflammation, and the structural degradation of mature neurons, typical of conventional dose-rate exposures, were resolved significantly in a preclinical mouse model exposed to FLASH radiotherapy. These benefits persisted over a 6-mon postirradiation interval and were caused, in part, by a mechanism involving reduced reactive oxygen species. Since normal tissue injury during and following radiotherapy dictates the maximum tolerated dose, the capability to ameliorate these adverse side effects holds significant promise for improving therapeutic outcome for cancer survivors worldwide.
Publisher: Springer Science and Business Media LLC
Date: 2002
Publisher: American Chemical Society (ACS)
Date: 1994
DOI: 10.1021/J100053A030
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.APRADISO.2007.07.034
Abstract: An alpha-spectrometry, using automated borate fusion and sequential extraction and exchange chromatography, was used to determine the uranium and thorium based on environmental radioactivity of 20 soil s les. The same set of the s les was analysed using gamma-spectrometry with an HPGe detector. The two data sets were checked for coherence using Z-score and chi2 statistical tests. We show that gamma-spectrometry is a valid alternative to time-consuming alpha-spectrometry for the determination of natural uranium and thorium activity in soil (activity range: 12.5-58.2 Bq/kg). The measured activities were compared with the theoretical activities to ensure secular equilibrium in the 238U and 232Th series. For 226Ra, a special study was made on deconvolution of the 186 keV multiplet with the Levenberg-Marquardt algorithm. Finally, the combined use of Z-score and chi2-tests was found to be a powerful tool for comparing the results obtained with two different methods.
Start Date: 2018
End Date: 2021
Funder: Swiss National Science Foundation
View Funded ActivityStart Date: 2009
End Date: 2012
Funder: National Commission for Science, Technology and Innovation
View Funded Activity