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The tetraneutron has attracted the attention of nuclear physicists during the past decades, but there is still no unambiguous confirmation of its existence or non-existence. A new experiment based on $$^{8}$$ He(p, 2p) $$^{7}$$ H{t+ $$^{4}n$$ } reaction, with direct detection of the four neutrons, has been carried out at RIBF, which can hopefully help to draw a definite conclusion on the tetraneutron system.

7 pags., 3 figs. -- 27th International Nuclear Physics Conference (INPC2019), The tetraneutron has attracted the attention of nuclear physicists during the past decades, but there is still no unambiguous confirmation of its existence or nonexistence. A new experiment based on 8 He(p,2p)7H{t+4n} reaction, with direct detection of the four neutrons, has been carried out at RIBF, which can hopefully help to draw a definite conclusion on the tetraneutron system., We acknowledge the support of the RIBF accelerator staff and the BigRIPS team for providing the high-quality beam. Z. H. Yang acknowledges the financial support from the Foreign Postdoctoral Researcher program of RIKEN. T. Aumann acknowledges the support by DFG via SFB 1245. P. Koseoglou acknowledges the support from BMBF (NUSTAR.DA grant No.05P 15RDFN1).

The MUGAST-AGATA-VAMOS set-up at GANIL combines the MUGAST highly-segmented silicon array with the state-of-the-art AGATA array and the large acceptance VAMOS spectrometer. The mechanical and electronics integration copes with the constraints of maximum efficiency for each device, in particular {\gamma}-ray transparency for the silicon array. This complete set-up offers a unique opportunity to perform exclusive measurements of direct reactions with the radioactive beams from the SPIRAL1 facility. The performance of the set-up is described through its commissioning and two examples of transfer reactions measured during the campaign. High accuracy spectroscopy of the nuclei of interest, including cross-sections and angular distributions, is achieved through the triple-coincidence measurement. In addition, the correction from Doppler effect of the {\gamma}-ray energies is improved by the detection of the light particles and the use of two-body kinematics and a full rejection of the background contributions is obtained through the identification of heavy residues. Moreover, the system can handle high intensity beams (up to 108 pps). The particle identification based on the measurement of the time-of-flight between MUGAST and VAMOS and the reconstruction of the trajectories is investigated., Comment: 13 pages, 18 figures

MgNi alloys prepared by mechanical alloying were coated with Pd nanoparticles via a polyol process. Such a process allows the deposition of fine particles of metal catalysts on the MgNi alloy surface. This surface modification leads to a strong improvement of the H storage performances of the alloy. The hydrogen release at 150 °C increases from 0.6 wt.% for uncoated MgNi alloy to 1.5 wt.% for a 5 wt.% Pd-coated MgNi alloy. The strong enhancement of the desorption capacity probably results from the catalytic effect of Pd, which may act as a hydrogen pump, thus favoring hydrogen migration from the bulk to the surface of the alloy.

Qualitative and quantitative X-ray analysis using the Rietveld method of the as cast ZrCr 0.7 Ni 1.3 alloy, shows an average phase abundance of 62.7% C15-Laves phase, 36.6% of Zr 7 Ni 10 and less than 1% of chromium. The annealed alloy at 1373 K reveals a complete disappearance of pure Cr with an important reduction of the amount of the Zr 7 Ni 10 phase based on EDS/SEM and XRD results. Pressure-Composition-Temperature (PCT) measurements show that the alloy behaves as a single phase with faster kinetics. Electrochemical measurements shows a relatively high discharge capacity of the cast alloy, c =320 mAhg −1 after 20 cycles. Contrary to that, the discharge capacity of the annealed alloy decreases by about a factor of 2 with c =156 mAhg −1 .

The optimization of the ball milling parameters resulted in the synthesis with a milling duration equal to 10 hours of amorphous MgNi having an initial discharge capacity over 520 mAh/g. Further milling results in a partial crystallization of amorphous MgNi into nanocrystalline MgNi 2 and Mg2Ni, which decreases significantly the electrode performance. This study also shows that it is possible to obtain an amorphous and electroactive material in large scale (1 kg of alloy per batch) using an industrial high-energy attritor. In addition, it was demonstrated that the carbon added at the beginning of the milling to avoid powder welding, in spite of its small proportion (1 wt.%), has a notable influence on the performance of the material. This study also confirms the major loss of activity during cycles. However, the partial substitution of Ti for Mg leads to a remarkable improvement of the cycle lifetime of the alloy.

The CaNi 5 -based alloys were synthesized by mechanical alloying followed by a low temperature annealing. Study shows that both substitution and annealing treatment affect the hydrogen storage capacity. Mm substitution for Ca results in an increased plateau pressure. The Zn and Al substitution for Ni leads to a bigger unit cell volume, a lower plateau pressure and a reduced capacity. Annealing treatment of the mechanically alloyed CaNi 5 -based alloys is a necessary process for obtaining good hydrogen storage capacity. The synthesized Ca-Mm-Ni-Zn-Al multicomponent nanocrystalline alloys exhibit fast kinetics on gas phase and electrochemical reaction and significantly improved cycle stability on electrochemical reaction.

We report on the synthesis of an electrochemically active Mg0.9Y0.1Ni polynanocrystalline phase by mechanical alloying. This alloy presents an initial capacity of 323 mAh/g that decreases upon cycling to reach a stable value of 220 mAh/g after 30 complete charge/discharge cycles (e.g. 62% capacity retention). Such an increase in capacity retention with respect to pure MgNi alloy (62% instead of 24%) is due to the addition of yttrium that enhances the resistance of the alloy against corrosion in concentrated alkaline media.

LiMn 2 O 4 -based Li-ion cells suffer from a limited cycle-life and a poor storage performance at 55°C, both in their charged and discharged states. From 3-electrode type electrochemical measurements, the non-stability of LiMn 2 O 4 in electrolytes containing traces of HF was identified as being the source of such a poor performance. To get some insight in the mechanism by which the high-temperature ageing proceeds, a survey of the chemical stability of high surface area LiMn 2 O 4 in various Li-based electrolytes was performed as a function of temperature. The growth of a protonated λ-MnO 2 phase was identified when LiMn 2 O 4 powders were stored into the electrolyte at 100°C for several hours. Such a protonated phase is partially inactive with respect to lithium intercalation, thereby accounting for some of the irreversible capacity loss experienced at 55°C for LiMn 2 O 4 -based Li-ion cells.

The effect of mechanical milling on powder mixtures consisting of graphite and AB{sub 5} alloys, prepared either by mechanical alloying or by a high-temperature melting process, has been investigated. The resulting hydride-forming composite electrodes show a 10 and 40% capacity enhancement for arc-melted and mechanically prepared AB{sub 5} alloys, respectively. Such an increase in capacity is suggested to be the result of several cumulative effects: (1) a mechanically induced reducing role of graphite which eliminates the AB{sub 5} particles of oxide coatings, enabling a better hydrogen adsorption/absorption and diffusion into the insertion sites of the alloy, (2) the appearance of an increasingly important double-layer capacitance on each particle with increased milling time that adds to the faradic component, and (3) the improved electronic conductivity between the active AB{sub 5} material and the graphite that allows a better utilization of the alloy.

Crystallized Mg2Ni and Mg2Ni2 amorphous alloys synthesized by mechanical alloying at room temperature were found to present first discharge capacities of 270 mAh/g and 500 mAh/g, respectively. These capacities decrease upon subsequent cycling to reach 30 mAh/g and 70 mAh/g after 60 charge/discharge cycles. The largest initial capacity, measured for the Mg2Ni2 composition, is ascribed to its amorphous nature, while its poor capacity retention upon cyding appears to originate from a fine Ni dispersion within the Mg/Ni matrix. This dispersion enables a better protection of the Mg against oxidation during cycling. We show, however, that this protection of Mg by Ni is not sufficient to avoid a strong corrosion of Mg in the KOH electrolyte during cycling, leading to the formation of Mg(OH)2.

Le contexte de la prevention comme ligne de repere des projets technologiques Depuis de nombreuses annees, les technologies se renouvellent en termes d’innovations (materiaux, substrats, composants, logiciels…), et aussi en termes d’applications sectorielles. Les TIC. : Technologies de l’Information et de la Communication n’echappent pas a ce foisonnement et permettent ainsi d’elargir le debat du progres technologique au sein meme de la societe. Les technologies de type RFID (identification par radiofrequence) quittent peu a peu le statut de technologie emergente pour s’affirmer comme une reponse possible a de nombreux secteurs (agro-alimentaire, logistique…). Le secteur de la sante n’echappe pas a cette diffusion technologique et le spectre applicatif [1] se deploie regulierement (identification et localisation des personnes, identification des equipements et des instruments chirurgicaux, gestion des echantillons de laboratoires, gestion du linge, soins a domicile). L’ARACT (association regionale pour l’amelioration des conditions de travail), associee a la CARSAT (caisse d’assurance retraite et de la sante au travail) et au CITC (centre d’innovation des technologies sans contact) – EuraRFID, a saisi l’opportunite d’un travail pluridisciplinaire [2] pour saisir les elements specifiques lies a l’integration de ces technologies dans le milieu du secteur sanitaire et social (maison de retraite – EPHAD (etablissement d’hebergement pour personnes âgees dependantes…). De nombreux travaux emaillent [3] les problematiques issues de l’integration des technologies dans l’environnement du travail (situations de travail, organisation du travail, espaces de travail…). L’evaluation des risques englobe des actions d’identification et de classement des risques, associees a la mise en place d’actions de prevention qui trouvent leur transcription dans le document unique. Quelques elements de retours d’experiences Le REX (dispositif de retour d’experiences) concernant l’integration des RFID dans un foyer logement (equipement des mouvements des personnes âgees a travers une montre) a permis de reveler les manques lies a une analyse des besoins prealable n’integrant pas l’environnement global du projet ainsi qu’une trop faible association des usagers et des salaries au projet (non fiabilite des capteurs, interoperabilite des systemes, faible integration des conditions de travail…). L’experience montre aussi que les phases de preparation et d’initiation du personnel salarie permettent de lever les ambiguites, les deceptions et les attentes non pourvues par le systeme. Trois dimensions essentielles caracterisent alors l’analyse prealable du projet RFID au sein de secteur : performance, conditions de travail et conduite de projet. Ainsi, pour reussir le deploiement d’une technologie de type RFID ou NTIC, il convient de concevoir le deploiement des usages futurs. Les travaux menes nous permettent de distinguer un cycle de projet [4] pour lequel la maitrise de la conception ne saurait se contenter de l’integration des specifications techniques des produits mais, de mettre en œuvre dans ce cycle, une phase essentielle d’appropriation par les usagers qui depasse les simples reunions de presentation des technologies. Pour une conception orientee vers les usages La dimension organisationnelle des projets technologiques associee a la participation des salaries a la conduite du projet permet de structurer l’organisation comme un objet lui-meme d’innovation. « L’ergonomie a ete ainsi sollicitee pour collaborer sous differentes formes avec les ingenieurs afin de leur fournir des orientations, principes, normes et parametres ergonomiques et/ou pour travailler directement avec les equipes projets » [5] . Une grille d’analyse permet d’etudier les impacts d’un projet d’implantation NTIC sur les differents points (objectifs, choix technologiques, conduite de projet, impacts metiers et emploi, effets–sante et organisation du travail). La Fig. 1 rend compte de l’emergence du cycle de vie d’un projet RFID qui tente de combiner a la fois la qualite de vie au travail, la sante et l’organisation du travail. Les differents projets developpes a ce jour montrent la necessite d’un cadre methodologique prealable a l’integration du facteur humain au sein des projets technologiques pour lesquels les techniques de simulation [6] peuvent etre sollicitees.

Two types of intermetallic compounds, LaNi 4 M with M=Mn, Co, Cu and Al and polysubstituted alloys Mm(NiAlMnCo) 5 with Mm=Mischmetal were synthesized by mechanical alloying. In most cases, 10 h grinding was sufficient to obtain single phase alloys with crystallites of about 6 nm and particles ranging between 5 and 80 mm in diameter. The polysubstituted MmNi 3.6 Al 0.35 Mn 0.25 Co 0.8 alloys, once removed from the grinding container, were found to present an electrochemical capacity of 159 mA h/g. Such a capacity was increased to 216.3, 241.7 and 273.5 mA h/g by a post-anneal step under vacuum to temperatures of 673, 873 and 1073 K, respectively. The various electrochemical capacity depends on both surface states and internal strains in the sample so that the heat treatments release these strains and enhance the capacity.

The effect of the carbon precursors morphology during a mechanical grinding experiment on the physical/electrochemical properties of the resulting ball-milled carbonaceous powders was studied. These properties strongly depend on the type of grinding mode used (shear or shock-type grinding); however, for each grinding mode, they were found to be totally independent of the nature of the precursor used (graphite, carbon, coke) and/or of its morphology (layers, microbeads and fibres). Eighty h of shock-grinding was found to produce carbonaceous milled powders able to reversibly intercalate two lithiums per six carbons `Li 2 C 6 ' while still having an irreversible capacity of 0.8 Li. The transparency of the precursor morphology and nature to mechanical grinding with carbon materials is ascribed to the strong 2D character of the graphite structure. Finally, the observed large reversible capacity in our hydrogen-free carbonaceous milled samples is explained on the basis of the previously proposed `house of cards' model.

The crack resistance of sheet asbestos cement has been characterized in terms of anR-curve which can accomodate effects which often influence the measurement of the critical stress intensity factorKc. The detection and location of the acoustic emission (AE) obtained from the asbestos cement has shown that it originates from microcracks in a zone just in front of the crack. The size of this zone increases to a maximum during slow propagation of the major crack and afterwards remains of constant size during the final crack growth. The form of theR-curve has been explained in terms of the mechanisms of fracture with the aid of AE and fractography studies. An analytical study has related the experimentalR-curve to a theoreticalR-curve and, hence, to the volume fraction, fibre aspect ratio and the strength of the fibre—matrix interface. It has been shown that the microcracking zone can be considered as a theoretical extension, of about one third of the zone length, to the real crack length.