Absence of low-temperature dependence of the decay of 7Be and 198Au in metallic hosts

The electron-capture (EC) decay rate of 7Be in metallic Cu host and the beta-decay rate of 198Au in the host alloy Al-Au have been measured simultaneously at several temperatures, ranging from 0.350 K to 293 K. No difference of the half-life of 198Au between 12.5 K and 293 K is observed to a precision of 0.1%. By utilizing the special characteristics of our double-source assembly, possible geometrical effects that influence the individual rates could be eliminated. The ratio of 7Be to 198Au activity thus obtained also remains constant for this temperatures range to the experimental precision of 0.15(0.16)%. The resulting null temperature dependence is discussed in terms of the inadequacy of the often-used Debye-Huckel model for such measurements.Comment: Four pages, three figures. Accepted for publication in Phys. Rev. C (Rapd Communications

A New Precision Measurement of the 7Be(p,gamma)8B Cross section with an Implanted 7Be Target

The 7Be(p,gamma)8B reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted 7Be target, a raster scanned beam and the elimination of the backscattering loss. The new measurement incorporates a more abundant 7Be target and a number of improvements in design and procedure. The point at Elab=991 keV was measured several times under varying conditions, yielding a value of S17(Ec.m. =850 keV) = 24.0(5) eV b. Measurements were carried out at lower energies as well. Due to the precise knowledge of the implanted 7Be density profile it was possible to reconstitute both the off- and on resonance parts of the cross section and to obtain from the entire set of measurements an extrapolated value of S17(0)=21.2(7) eV b.Comment: 4 Pages, 3 Figure

Astrophysical S factor for the He-4(He-3,gamma)Be-7 reaction at medium energies

3 pags., 1 tab. -- Nuclear Physics in Astrophysics V 3–8 April 2011, Eilat, IsraelThe astrophysical S factor for the He-4(He-3,gamma)Be-7 direct capture reaction plays a major role in the context of solar neutrino flux and primordial Li-7 abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of E-CM=900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor

Duration of Treatment for Pseudomonas aeruginosa Bacteremia : a Retrospective Study

Introduction: There is no consensus regarding optimal duration of antibiotic therapy for Pseudomonas aeruginosa bacteremia. We aimed to evaluate the impact of short antibiotic course. Methods: We present a retrospective multicenter study including patients with P. aeruginosa bacteremia during 2009-2015. We evaluated outcomes of patients treated with short (6-10 days) versus long (11-15 days) antibiotic courses. The primary outcome was a composite of 30-day mortality or bacteremia recurrence and/or persistence. Univariate and inverse probability treatment-weighted (IPTW) adjusted multivariate analysis for the primary outcome was performed. To avoid immortal time bias, the landmark method was used. Results: We included 657 patients; 273 received a short antibiotic course and 384 a long course. There was no significant difference in baseline characteristics of patients. The composite primary outcome occurred in 61/384 patients in the long-treatment group (16%) versus 32/273 in the short-treatment group (12%) (p = 0.131). Mortality accounted for 41/384 (11%) versus 25/273 (9%) of cases, respectively. Length of hospital stay was significantly shorter in the short group [median 13 days, interquartile range (IQR) 9-21 days, versus median 15 days, IQR 11-26 days, p = 0.002]. Ten patients in the long group discontinued antibiotic therapy owing to adverse events, compared with none in the short group. On univariate and multivariate analyses, duration of therapy was not associated with the primary outcome. Conclusions: In this retrospective study, 6-10 days of antibiotic course for P. aeruginosa bacteremia were as effective as longer courses in terms of survival and recurrence. Shorter therapy was associated with reduced length of stay and less drug discontinuation

A combined process for the selective rare earth recovery and separation from used permanent magnets

International audienceRare earth elements (REE) have become essential for our modern economy, in relation to the development of new energy and communication technologies. Albeit being considered today as the most critical raw materials group with the highest supply risk, the recycling of REE from electronic waste and end-of-life products (permanent NdFeB magnets, Ni-MH batteries etc.) is almost inexistent.[1] Therefore, a large research effort is needed for over-coming the current scientific and technological barriers and improving the recycling efficiency. Innovative, eco-designed processes have to be developed, which require extensive RandD effort from basic research to technological developments.The CEA has gained a world-class expertise in the field of separation processes by hydrometallurgy and pyrometallurgy, several solvent extraction processes being developed and industrially implemented for the nuclear fuel cycle. In this communication, an efficient combined hydro- and pyrometallurgical process aimed at REE recovery and separation from used NdFeB permanent magnets will be presented.[2] The process integrates the mechanical and physico-chemical treatment of NdFeB magnets, followed by a liquid-liquid solvent extraction step for the recovery and intra-separation of REE using a selective extractant with excellent affinity for heavy REE which are today the most expensive REE. Experimental liquid-liquid extraction and modeling data allowing the recovery of a 99.9 per cent pure Dysprosium solution will be discussed in this paper. A subsequent pyrometallurgical treatment via molten chloride salt electrolysis allowed the isolation of pure Dy metal with 80 per cent faradic yield. This is one of the first examples of an effective, closed-loop REE recovery and separation process, starting from magnet scrap down to individual pure REE as metals, which paves the way for future developments in the field.Following this successful demonstration, a new project aimed at the separation of rare earths and nickel from Ni-MH batteries is currently being developed in our department, and preliminary results concerning the evaluation of new molecules for liquid-liquid extraction will be presented in this paper

Development of a new process for the selective rare earth recovery from used permanent magnets

International audienceAlbeit being considered today as the most critical raw materials group with the highest supply risk, the recycling of rare earth elements (REE) from permanent NdFeB magnets is almost inexistent. Therefore, a large research effort is needed for over-coming the current scientific and technological barriers and improving the recycling efficiency. Innovative, profitable and eco-designed processes have to be developed, which require extensive R&D effort from basic research to technological developments. The CEA has gained a world-class expertise in the field of separation processes by hydrometallurgy and pyrometallurgy, several solvent extraction processes being developed and industrially implemented for the nuclear fuel cycle. In this communication, an efficient combined hydro- and pyrometallurgical process aimed at REE recovery and separation from used or refurbished NdFeB permanent magnets will be presented. The process integrates the mechanical and physico-chemical treatment of NdFeB magnets, followed by a solvent extraction step for the recovery and intra-separation of REE using a selective extracting molecule with excellent affinity for heavy REE (Dysprosium) which are today the most critical REE. A solvent extraction flow sheet was calculated and tested in laboratory-scale mixer-settlers from a genuine solution of permanent magnets leached in nitric acid. More than 99.9% of dysprosium and neodymium were recovered in two different streams with purities higher than 99.99%. A subsequent pyrometallurgical treatment via molten chloride salt electrolysis allowed the isolation of pure Dy metal with excellent faradic yields. Based on these results, a first techno-economic analysis was made to scale-up the process at an industrial scale and will be presented in the paper. This is one of the first examples of an effective, closed-loop REE recovery and separation process, starting from magnet scrap down to individual pure REE as metals, which paves the way for future developments in the field

A combined hydro- and pyrometallurgical process for REE recovery from used permanent magnets

International audienceRare earth elements (REE) have become essential for our modern economy, in relation to the development of new energy and communication technologies. Albeit being considered today as the most critical raw materials group with the highest supply risk, the recycling of REE from electronic waste and end-of-life products (permanent NdFeB magnets, Ni-MH batteries etc.) is almost inexistent. Therefore, a large research effort is needed for overcoming the current scientific and technological issues and improving the recycling efficiency. Innovative, eco-designed processes have to be developed, which require extensive RandD effort from basic research to technological developments

Future challenges in hydrometallurgy for critical metal recovery and recycling RadioChemistry and Processes Department CEA Marcoule

International audienceThe demand for certain critical metals including rare-earths has recently increased, in relation to the development of new energy and communication technologies. Various initiatives such as recycling and prospection of new resources have been launched to reduce the European dependence on foreign suppliers. Hydrometallurgy is essential for the valorization of these poly-metallic resources in which the critical elements are often in low concentrations among numerous impurities. Innovative and environmental-friendly processes have to be developed to recover these elements, which require extensive RetD from basic research to technological developments.The CEA has gained a world-class expertise in the field of separation processes by hydrometallurgy. Several solvent extraction processes have been developed and industrially implemented for the nuclear fuel cycle. More recently, CEA developed processes to support the recycling of critical materials for energy technologies (Li-ion batteries, fuel-cells). In this framework, the RECAPE project aims to develop an efficient recovery process of heavy rare-earth elements by hydrometallurgy from used permanent magnets. Experimental and modeling results will be presented in this paper. More generally, CEA aims to enhance the coordination and integration of the European community in the field of RetD on critical materials recovery and recycling. This strategy will include both the creation of a European Institute of Hydrometallurgy to allow the industrial qualification of separation processes and the launching of a European research network to support innovation in the field of critical metals

A new measurement of the proton capture rate on 7^{7}Be and the S17_{17}(0) factor

The $^{7}$Be(p, $\gamma$) \,^{8}B reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted target, a raster scanned beam and the elimination of back-scattering losses. The new measurement incorporates a higher activity $^{7}$Be target and a number of improvements in design and procedure. The cross section at Ec.m. = 850 keV was measured several times under varying experimental conditions, yielding a value of S$_{17}$(Ec.m.=850 keV) = 24.0 $\pm$ 0.5 eV b. Measurements were carried out at lower energies as well. We obtain from the entire set of measurements an extrapolated value of S$_{17}$(0) = 21.2 $\pm$ 0.7 eV b