High-temperature oxidation resistance of chromium-based coatings deposited by DLI-MOCVD for enhanced protection of the inner surface of long tubes

For nuclear safety issues, there is an international effort to develop innovative “Enhanced Accident Tolerant Fuels” (EATF) materials. EATF cladding tubes are of particular interest because they constitute the first barrier against radioactive fission species dispersal in case of accidental scenario such as LOCA (LOss of Coolant Accident). Actual nuclear fuel claddings are made from Zr-based alloys and to increase safety margins, both mechanical strength and resistance to high-temperature oxidation have to be improved. Several alternatives using high-temperature oxidation resistant coatings for outer-wall protection have been proposed worldwide but there is currently no solution for the inner-wall protection. In order to resist to high temperature steam environment upon LOCA transients, internal Cr-based coatings deposited by DLI-MOCVD (Direct Liquid Injection of MetalOrganic precursors) were investigated. These hard metallurgical coatings could also be used in high-temperature corrosive environments as those encountered in aeronautics and other industries to protect 3D complex components. Thanks to a suitable chemistry of the liquid Cr precursor, bis(ethylbenzene)chromium, different coatings were deposited including: metal Cr, chromium carbides CrxCy and mixed carbides CrxSizCy. The high-temperature behavior of these Cr-based coatings under oxidizing atmospheres has been studied using several techniques and various oxidation tests including pure steam environment followed by water quenching down to room temperature to be representative of LOCA situations. Amorphous CrxCy coatings showed the most promising properties. For instance compared to uncoated substrate, they shift the catastrophic oxidation towards higher temperatures and delay the complete oxidation of the substrate at 1473K of >2h. The results are discussed in terms of oxidation mechanisms and protection of the fuel claddings inner surface deduced from fine characterizations of the samples before and after oxidation tests

Supporting patient-clinician interaction in chronic HIV care: Design and development of a patient-reported outcomes software application

Background: The consideration of health-related quality of life (HRQL) is a hallmark of best practice in HIV care. Information technology offers an opportunity to more closely engage patients with chronic HIV infection in their long-term management and support a focus on HRQL. However, the implementation of patient-reported outcome (PRO) measures, such as HRQL in routine care, is challenged by the need to synthesize data generated by questionnaires, the complexity of collecting data between patient visits, and the integration of results into clinical decision-making processes. Objective: Our aim is to design and pilot-test a multimedia software platform to overcome these challenges and provide a vehicle to increase focus on HRQL issues in HIV management. Methods: A multidisciplinary team in France and Australia conducted the study with 120 patients and 16 doctors contributing to the design and development of the software. We used agile development principles, user-centered design, and qualitative research methods to develop and pilot the software platform. We developed a prototype application to determine the acceptability of the software and piloted the final version with 41 Australian and 19 French residents using 2 validated electronic questionnaires, the Depression, Anxiety and Stress Scale-21 Items, and the Patient Reported Outcomes Quality of Life-HIV. Results: Testing of the prototype demonstrated that patients wanted an application that was intuitive and without excessive instruction, so it felt effortless to use, as well as secure and discreet. Clinicians wanted the PRO data synthesized, presented clearly and succinctly, and clinically actionable. Safety concerns for patients and clinicians included confidentiality, and the potential for breakdown in communication if insufficient user training was not provided. The final product, piloted with patients from both countries, showed that most respondents found the application easy to use and comprehend. The usability testing survey administered found that older Australians had reduced scores for understanding the visual interface (P=.004) and finding the buttons organized (P=.02). Three-fourths of the respondents were concerned with confidentiality (P=.007), and this result was more prevalent in participants with higher anxiety and stress scores (P=.01), as measured by the Depression, Anxiety and Stress Scale-21 Items. These statistical associations were not observed in 15 French patients who completed the same questionnaire. Conclusions: Digital applications in health care should be safe and fit for purpose. Our software was acceptable to patients and shows potential to overcome some barriers to the implementation of PROs in routine care. The design of the clinicians’ interface presents a solution to the problem of voluminous data, both synthesizing and providing a snapshot of longitudinal data. The next stage is to conduct a randomized controlled trial to determine whether patients experience increased satisfaction with care and whether doctors perceive that they deliver better clinical care without compromising efficiency

La Maqālat Balʽam, Traité sur Balaam, un traité samaritain inédit

The Maqālat Bal' am, a previously unpublished Samaritan treatise, is translated from a manuscript transmitted by the High Preast Eleazar b. Ṣadaqah and Abraham Tal. It shows a commentary in Arabic about the story of Balaam as it appears in the Hebrew version of Numbers 22-24 ; 31,8.16.La Maqālat Bal 'am, traité samaritain inédit, est ici traduit à partir d’un manuscrit transmis par le Grand Prêtre Eléazar b. Ṣadaqah et Abraham Tal. Elle nous présente un commentaire en arabe de l’histoire de Balaam telle qu’elle se présente en hébreu en Nombres 22-24 ; 31,8.16.Bonnard Christophe, Donzé-Michau Marie-Christine. La Maqālat Balʽam, Traité sur Balaam, un traité samaritain inédit. In: Revue d'histoire et de philosophie religieuses, 89e année n°3, Juillet-Septembre 2009. pp. 289-311

Imaging concentration fields in microfluidic fuel cells as a mass transfer characterization platform

Microfluidic fuel cells (MFCs) are microfluidic electrochemical conversion devices that are used to power electrical equipment. Their performance relies on improving reactant mass transfer at the electrode interface. In this work, a MFC is developed to implement a novel imaging technique that allows the measurement of reactant concentration fields, featuring formic acid as the fuel and potassium permanganate as the oxidant. The concentration fields were imaged based on transmitted visible spectroscopy, which links the light intensity passing through the MFC to its local reactant concentration. An analytical model was developed to estimate the mass diffusivity and kinetic reaction rate coefficient. For the first time, mass transport and transfer coefficient were simultaneously measured during operation. These parameters estimated using the proposed technique can be implemented in a numerical model to predict the MFC performance and concentration distribution. This work paves the way towards advanced imaging tools for operando mass transfer characterizations in microfluidics and Tafel kinetic characterization in many electrochemical devices.IMagerie Multiphysique des Piles A Combustible microfluidique

Iron-clay interactions under hydrothermal conditions: Impact of specific surface area of metallic iron on reaction pathway

International audienceThe long-term evolution of minerals in contact with metallic iron is important in various domains such as the earth sc iences, materials science, cosmochemistry or industry. As an illustration, iron-clayey rock interactions are notable issues in the framework of secondary alteration processes in chondrites, or in the evolution of steel canister corrosion in projects for high-level nuclear waste repositories. In these contexts, interactions between the geological environment and metallic iron or engineered structures must be assessed with a high level of precision. Therefore, over the last decade, several experimental studies have focused on metallic iron-clay interactions showing the important relationship between the reaction progress and the iron/clay mass ratio. The present investigation demonstrates that, apart from this mass ratio, the specific surface area of metallic iron has a crucial influence, since it impacts the reaction pathway and the ambient physico-chemical parameters of the medium. For this purpose, two original continuous monitoring experiments were performed to measure pH and pressure in real-time, as well as analyze the gas and solution compositions, by bringing the same mass of (a) iron powder (S-iron = 0.07 m(2)/g) or (b) iron grains (Siron approximate to 0.001 m2/g) into contact with claystone (Callovo-Oxfordian claystone, Bure, France) at 90 degrees C for 3 months. Using iron powder, i. e. the more reactive cast iron (with a corrosion rate of 0.54 mmol/day for iron powder as against 0.01 mmol/day for iron grains), causes an Fe-enrichment of the clay particles, leading initially to the formation of new phases intermediate between interlayered illite-smectite and iron-rich serpentine, followed by conversion into odinite-greenalite. On the other hand, using iron grains make the clay compositions ``kaolinitic'' with a noticeable I. C. depletion. Meanwhile, the illite-smectite and quartz fractions of the claystone are destabilized, while the mineral transformations control the pH around 7 (+/-0.3) and prevent the formation of magnetite, thus contradicting the thermodynamic predictions. The present study, which involves in situ monitoring of pH and H-2 production, provides some important keys to obtaining better constraints on reaction mechanisms, kinetics and thermodynamic models, aimed at predicting accurate reaction paths and their long-term consequences

Cool-SPS stabilization and sintering of thermally fragile, potentially magnetoelectric, NH4FeP2O7

Cool-SPS conditions (low temperature/high pressure) can be used to densify materials with limited thermodynamical stability, due to low temperature phase transition, melting, decomposition… We recently demonstrated the potential of SPS for the stabilization and densification of diversified materials at very low temperatures. Here we report the sintering of a potentially magnetoelectric pyrophosphate with low temperature decomposition. Characterization of its magnetic properties are presented, and dielectric/magnetoelectric characterization could also be performed thanks to the high densification obtained at temperatures as low as 200 °C

Chemical evolution of a HLW cell in Callovo-Oxfordian Claystone: taking into account the oxic transient period

International audienceNumerous calculations have been performed to represent the long-term chemical evolution of theautochthonous (e.g. argillaceous rock) and allochthonous (e.g. cement based materials, carbon steel)materials that may interact within the French underground radioactive waste repository concept. Theoxic transient related to the operating period (due to the access drift ventilation) in High-Level andlong-lived Waste (HLW) repository facilities is often neglected in the simulation of their long-termchemical evolution. However the initial oxidation of the reduced environment prevailing in theclaystone and the oxic corrosion of the carbon steel in the HLW cell head combined with the anoxiccorrosion of the carbon steel and H2 production in the using part of the cell may lead to a complexoxidizing/reducing front (De Windt et al., 2014). The present study intends to simulate the transitionphase between the periods with oxidative and reductive conditions in order to determine:• how the chemical compositions of the metallic materials, clay and cement in the HLW cell arealtered by atmospheric oxygen and carbon dioxide during the operating period;• and how these alterations affect the long term chemical evolution of the system after closureof disposal cell.The modelling strategy relies on a two steps procedure. Two phases flow simulations were carried outwith Comsol Multiphysics, in order to obtain the temperature and water saturation profiles as afunction of the different operating steps. The chemical evolution of the HLW cell was then simulatedwith the reactive transport code CrunchFlow (Steefel et al., 2014) with fixed water saturation andtemperature profiles derived from the thermal-hydrology simulations. The code flexibility enabled thesimultaneous consideration of the irreversible reaction describing the pyrite oxidation by O2, andsubsequent sulphates release, and the reversible reaction of pyrite dissolution/precipitation underanoxic conditions. The simulation of the oxic period led to pyrite oxidative dissolution together withiron oxi(hydr)oxides and gypsum precipitations (Fig. 1). As a result of pyrite dissolution, the pH valuein the pore water decreased, but is rapidly buffered by carbonate dissolution at the wall of the drift.After the sealing of the disposal cell by addition of 3 meters of bentonite and 4 meters of concrete(2009 version of Andra’s concept), iron canister corrosion consumes the O2, which leads to theestablishment of reducing conditions. Once O2 is depleted, the canister corrosion then produces H2.Magnetite and siderite were simulated as being the main corrosion products. The alteration of the claymineralsunder reducing conditions was characterised primarily by a transformation of pyrite intopyrrhotite. In addition, formation of greenalite was simulated at the interface between the claystoneand the metallic material. Those two predictions are in agreement with results obtained on short termexperiments (Truche et al., 2009; Bourdelle et al., 2014). Simulation results indicated also adestabilization of the illite–smectite and quartz minerals of the claystone (Fig. 2)

Persistent type-II multiferroicity in nanostructured MnWO4 ceramics

In archetypal ferroelectrics, the polarization and related properties result from structural lattice distortions.1 For example, in BaTiO3, it is the cationic off-centering versus the oxygen octahedra that is at the origin of the exceptional dielectric properties. Keeping these properties when downsizing such compounds is thus a challenge because the lattice elastic energy is disturbed by the surface energy even at relatively large grain size of several hundreds of nm..

Phaeohyphomycosis due to Exophiala xenobiotica as a cause of fungal arthritis in an HIV-infected patient

International audienceBlack yeasts including Exophiala species are increasingly recognized as agents of human disease. In recent years, progress in molecular phylogeny and taxonomy of the genus Exophiala has led to the description of numerous novel species. The 'classical' but highly variable species Exophiala jeanselmei was split into a number of morphological siblings, which, however, were phylogenetically and clinically remote from each other. E. jeanselmei was restricted to an uncommon species causing subcutaneous infections. Hence only limited information is available on the segregants, among which is E. xenobiotica. We describe a case of an HIV-patient presenting with fungal arthritis and subcutaneous nodules caused by the latter species, which was identified by means of phenotypic and molecular methods

Greater diversity of HIV DNA variants in the rectum compared to variants in the blood in patients without HAART

International audienceThe gut-associated lymphoid tissue represents the largest reservoir of HIV-1. Improving knowledge of this reservoir by studying the diversity of viral population is a key step towards understanding the pathogenesis and dynamics of HIV. Obtaining samples is difficult and little information is available on gut viral quasispecies during the course of infection in humans. The aim of the study was to characterize rectal viral strains and their diversity and to investigate the relationships between the rectal tissue reservoir and viral variants in the blood. Phylogenetic analyses were performed on the env sequences for rectal HIV DNA, blood HIV DNA and HIV RNA clones, with maximum likelihood and neighbor-joining methods on seven patients. Genetic diversity was assessed. Higher diversity of HIV DNA clones was noted in the rectum compared to blood in 4 out of 5 patients without HAART. Viral diversity was present in the rectum from time of the primary infection. Similar degrees of diversity were observed in the rectum and blood during HAART. Rectal and blood HIV variants were interspersed partially or totally in the seven patients. A certain number of rectal HIV DNA clones were clustered together in six patients. These results suggest that variants in the rectum were more heterogeneous than variants in the blood from patients without HAART, probably because the activated milieu of gut-associated lymphoid tissue may provide an improved environment for viral replication, and indicate exchange of viral populations between blood and rectal tissues, reflecting the dynamics of HIV during course of infection