Innovative ICP-MS/MS Method To Determine the 135^{135}Cs/137^{137}Cs Ratio in Low Activity Environmental Samples

International audienceThe $^{135}$Cs/$^{137}$Cs isotopic ratio is a powerful tool for tracing the origin of radioactive contamination. Since the Fukushima accident, this ratio has been measured by mass spectrometry in several highly contaminated environmental matrices mainly collected near nuclear accident exclusion zones and former nuclear test areas. However, few data were reported at $^{137}$Cs environmental levels (<1 kBq kg$^{–1}$). This is explained by the occurrence of analytical challenges related to the very low radiocesium content at the environmental level with the large presence of mass interferences, making $^{135}$Cs and $^{137}$Cs measurements difficult. To overcome these difficulties, a highly selective procedure for Cs extraction/separation combined with an efficient mass spectrometry measurement must be applied on a quantity of ca. 100 g of soil. In the current research, an innovative inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) method has been developed for the $^{135}$Cs/$^{137}$Cs ratio measurement in low activity environmental samples. The use of ICP-MS/MS led to a powerful suppression of $^{135}$Cs and $^{137}$Cs interferences by introducing N$_2$O, He, and, for the first time, NH$_3$, into the collision-reaction cell. By adjusting the flow rates of these gases, the best compromise between a maximum signal in Cs and an effective interference elimination was achieved allowing a high Cs sensitivity of more than 1.10$^5$ cps/(ng g$^{–1}$) and low background levels at $m/z$ 135 and 137 lower than 0.6 cps. The accuracy of the developed method was successfully verified by analyzing two certified reference materials (IAEA-330 and IAEA-375) commonly used in the literature as validation samples and three sediment samples collected in the Niida River catchment (Japan) impacted by the Fukushima fallout

Epileptic spasms are associated with increased stereo‐electroencephalography derived functional connectivity in tuberous sclerosis complex

Objective: Epileptic spasms (ES) are common in tuberous sclerosis complex (TSC). However, the underlying network alterations and relationship with epileptogenic tubers are poorly understood. We examined interictal functional connectivity (FC) using stereo-electroencephalography (SEEG) in patients with TSC to investigate the relationship between tubers, epileptogenicity, and ES. Methods: We analyzed 18 patients with TSC who underwent SEEG (mean age = 11.5 years). The dominant tuber (DT) was defined as the most epileptogenic tuber using the epileptogenicity index. Epileptogenic zone (EZ) organization was This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made

Results of the EURAMET.RI(II)- S7.Sm-151 supplementary comparison (EURAMET Project 1292)

An international comparison of the activity standardisation of the relatively long-lived gamma-ray emitter 151Sm has been recently completed. A total of six laboratories measured a solution prepared by CEA/LNHB and CEA/LANIE. Aliquots of the master solution were standardized in terms of activity per mass unit by participant laboratories using 2 different techniques. The results of the comparison can be used as the basis for establishing equivalence among the laboratories. The activity measurements of this comparison are part of the joint research project “Metrology for Radioactive Waste Management” of the European Metrology Research Programme (EMRP). One aim of this project is a new determination of the 151Sm half-life.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Determination of the 151Sm half-life

New measurements have been undertaken to determine the half-life of 151Sm. A pure 151Sm solution was obtained after chemical separation from a samarium solution resulting from the dissolution of an irradiated samarium sample. The concentration of 151Sm in the solution was measured by mass spectrometry, combined with the isotope dilution technique. The activity of the solution was measured by liquid scintillation counting by six European laboratories as part of an international comparison. These combined results lead to a half-life of T1/2 = 94.6(6) a.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

The half-life of 129I

The radionuclide 129I is a long-lived fission product that decays to 129Xe by beta-particle emission. It is an important tracer in geological and biological processes and is considered one of the most important radionuclides to be assessed in studies of global circulation. It is also one of the major contributors to radiation dose from nuclear waste in a deep geological repository. Its half-life has been obtained by a combination of activity and mass concentration measurements in the frame of a cooperation of 6 European metrology institutes. The value obtained for the half-life of 129I is 16.14 (12) × 106 a, in good agreement with recommended data but with a significant improvement in the uncertainty.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard

Results of the EURAMET.RI(II)-K2.Ho-166m activity comparison

In 2013, five laboratories took part in the EURAMET.RI(II)-K2.Ho-166m comparison of activity concentration measurements of 166mHo. The activity measurements of this comparison are part of the joint research project “Metrology for Radioactive Waste Management” of the European Metrology Research Programme (EMRP). One aim of this project is a new determination of the 166mHo half-life.The results were found to be in good agreement and no outlier could be identified. A comparison reference value (CRV) has been calculated as the power-moderated mean (PMM) of all final laboratory results and was found to be 119.27(10) kBq g–1. Preliminary degrees of equivalence based on the Comparison Reference Value were also calculated for each reporting laboratory. The Key Comparison Reference Value and final degrees of equivalence will be calculated by the BIPM from the data contained herein and data from measurements made in the International Reference System (SIR).JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Qualification for Safeguards Purposes of UF6 Sampling using Alumina – Results of the Evaluation Campaign of ABACC-Cristallini Method

The procedure currently used to sample material from process lines in uranium enrichment plants consists of collecting the uranium hexafluoride (UF6) in gaseous phase by desublimation inside a metal sampling cylinder cooled with liquid nitrogen or in certain facilities in a fluorothene P-10 tube type. The ABACC-Cristallini method (A-C method) has been proposed to collect the UF6 (gas) by adsorption in alumina (Al2O3) in the form of uranyl fluoride (UO2F2) (solid). This method uses a fluorothene P-10 tube type containing alumina pellets that absorb and hydrolyze UF6 directly during the sampling. This new method has advantages compared to the usual method with less residual material left at the facility and also less constraint related to nuclear material transport regulation. ABACC invited seven international laboratories to participate in a UF6 sampling method evaluation campaign. This campaign involved high accuracy measurement of uranium isotopics sampled as UF6 using two different sampling methods: Adsorption on alumina (A-C method) and a standard direct hydrolysis method. The goal of the campaign was to determine if there is any detectable difference in the isotopic composition of UF6 materials when sampled by the two methods. Four different IRMM UF6 Certified Reference Materials were sampled by each of the methods to create four pairs of samples for analysis. Each sample was contained in a P-10 tube, and required dissolution and sample preparation prior to isotopic analysis. This paper presents the results obtained from seven laboratories which will be used for the technical certification process that ABACC is pursuing for qualification of the UF6 sampling A–C method for uranium isotopic determination. The results will also be the basis of the validation process to confirm that the new method can be used for routine safeguards application at the enrichment plants.JRC.G.II.6-Nuclear Safeguards and Forensic

Genome-wide association analysis in dilated cardiomyopathy reveals two new players in systolic heart failure on chromosomes 3p25.1 and 22q11.23

AIMS : Our objective was to better understand the genetic bases of dilated cardiomyopathy (DCM), a leading cause of systolic heart failure. METHODS AND RESULTS : We conducted the largest genome-wide association study performed so far in DCM, with 2719 cases and 4440 controls in the discovery population. We identified and replicated two new DCM-associated loci on chromosome 3p25.1 [lead single-nucleotide polymorphism (SNP) rs62232870, P = 8.7 × 10-11 and 7.7 × 10-4 in the discovery and replication steps, respectively] and chromosome 22q11.23 (lead SNP rs7284877, P = 3.3 × 10-8 and 1.4 × 10-3 in the discovery and replication steps, respectively), while confirming two previously identified DCM loci on chromosomes 10 and 1, BAG3 and HSPB7. A genetic risk score constructed from the number of risk alleles at these four DCM loci revealed a 27% increased risk of DCM for individuals with 8 risk alleles compared to individuals with 5 risk alleles (median of the referral population). In silico annotation and functional 4C-sequencing analyses on iPSC-derived cardiomyocytes identify SLC6A6 as the most likely DCM gene at the 3p25.1 locus. This gene encodes a taurine transporter whose involvement in myocardial dysfunction and DCM is supported by numerous observations in humans and animals. At the 22q11.23 locus, in silico and data mining annotations, and to a lesser extent functional analysis, strongly suggest SMARCB1 as the candidate culprit gene. CONCLUSION : This study provides a better understanding of the genetic architecture of DCM and sheds light on novel biological pathways underlying heart failure.Medical Genomic