Défluoruration des eaux par dialyse de Donnan et électrodialyse

Les travaux réalisés dans cette étude avaient pour objectif l'application de techniques membranaires, dialyse de Donnan et électrodialyse, au traitement d'eaux dont la teneur en fluorure est supérieure à la valeur maximale admissible. Ces deux techniques qui mettent en jeu des membranes échangeuses d'ions, se distinguent par la nature des forces motrices de transfert. Trois eaux modèles relatives à trois pays différents (Maghreb, Sénégal et France) ont été préparées et traitées sur pilotes pré-industriels. Dans tous les cas étudiés, bien que divers anions (Cl-, HCO3-, SO42-) et cations (Na+, K+, Ca2+, Mg2+) soient présents initialement dans les solutions à traiter, une concentration en fluorure conforme aux normes a pu être atteinte avec toutes les membranes testées.L'électrodialyse qui abaisse la teneur de tous les ions présents dans l'eau, anions et cations, entraîne une déminéralisation partielle et par conséquent un adoucissement de la solution traitée. Par contre, la dialyse de Donnan, du fait de la diffusion du sel du compartiment receveur vers la solution traitée, augmente légèrement la minéralisation initiale. Cette technique qui, du point de vue énergétique, est un procédé plus économique que l'électrodialyse, semble donc plus adaptée au traitement d'eaux fluorurées à faible minéralisation.The purpose of this work was to apply Donnan dialysis (DD) and electrodialysis (ED) for removing fluoride ion from waters where the concentration exceeds acceptable values. The techniques both use ion-exchange membranes but involve different driving forces: the difference in the electrochemical potential on both sides of the membrane for DD and the difference in the electric potential in ED.Both techniques were applied to treat model waters, the compositions of which were very close to those of natural waters contaminated by fluorides. Three standard waters related to three different countries (Maghreb, Senegal and France) were prepared and treated with pre-industrial pilots. The active membrane area was 1760 cm2 for Donnan dialysis, 552 and 2000 cm2 for electrodialysis. Two anion exchange membranes, DSV from Asahi Glass and AFX from Tokuyama Soda, were tested in Donnan dialysis. Three electrodialysis stacks equipped with different anion and cation exchange membranes, AMV-AM1/CMV from Asahi Glass, AMX/CMX and ACS/CMS from Tokuyama Soda, were used. Conductivity, pH and the concentrations of each ionic species were monitored during membrane treatment. The initial fluoride concentration were 9.5, 6.08 and 2.66 mg L-1 in each standard water, respectively.In all cases, despite the presence of different anions (Cl-, HCO3-, SO42-) and cations (Na+, K+, Ca2+, Mg2+) generally present in ground waters, a fluoride concentration in agreement to the norms (< 1.5 mg L-1) could be achieved regardless of the composition of the treated waters or the nature of the tested membranes. Electrodialysis decreased the anion and cation concentrations and induced a partial demineralization (about 70%) and consequently a softening of the treated water. On the contrary in Donnan dialysis, due to the electrolyte diffusion from the receiving compartment to the treated solution, the mineralization of the treated water increased slightly (about 10%). In this latter process, the anion concentration declined while no changes were observed in the cation concentration, except for sodium because of the electrolyte leakage. The DSV membrane was the most effective anion exchange membrane to use in DD. In ED, the AMV-AM1/CMV stack was selected on the basis of the demineralization and softening ratio, and the energy consumption.Donnan dialysis, which from an energy consumption point of view is more economical than ED, thus seems more adapted to the treatment of low mineralization waters

Challenges and opportunities in polysaccharides research and technology: The EPNOE views for the next decade in the areas of materials, food and health care

International audienceThe European Polysaccharide Network of Excellence (EPNOE) is a research and education network connecting 16 academic and research institutions and a large number of companies with its focus on polysaccharide expertise development and polysaccharide-related research for innovation in business and industry. EPNOE has two main missions in the field of polysaccharide applications in materials, food, and pharmacy/medicine, which are to organise education in polysaccharide science and to perform basic and applied research for the development of new products derived from polysaccharides. In 2009, the EPNOE network prepared a research road map vision to 2020 focussed on polysaccharide use in material structuring, food and health, taking both research and education into consideration. The research road map was prepared from various social, political, industrial and scientific inputs coming from within and outside EPNOE: (1) results of four brain-storming sessions by EPNOE scientists and students, (2) individual contributions of EPNOE scientists and (3) individual contributions of scientists outside EPNOE through an internet review. The result is described in this article

Talking About and Preparing for Death Among Older Adults

Experts on end-of-life issues recommend that individuals make preparations – living will, health care proxy, last will and testament, and memorial service – for their eventual death (Bischoff, Sudore, Miao, Boscardin, & Smith, 2013). While these experts further encourage a broader process of advance care planning, which includes conversations with loved ones, many individuals are reticent to engage in such end-of-life conversations (Brinkman-Stoppelenburg, Rietjens, & Heide, 2014). The purpose of this study was to investigate relationships between older adults’ comfort having end-of-life discussions with family members, death preparation, and comfort with their end-of-life plans. Community-dwelling older adults (N = 354) participated in an interview survey about end-of-life issues. Comfort with having end-of-life discussions with family was associated with greater death preparation and comfort with end-of-life plans. Death preparation mediated the relationship between comfort with end-of-life discussions and comfort with end-of-life plans. Overall, the results are consistent with the notion that individuals who are more comfortable discussing their end-of-life plans with loved ones engage in greater death preparation and thereby feel a greater sense of contentment with their plans for death

Computing Immutable Regions for Subspace Top-k Queries

National Research Foundation (NRF) Singapore under International Research Centre @ Singapore Funding Initiativ

Impact de quelques techniques de lavage sur la décontamination de tuiles et béton contaminés par du cesium et du strontium radioactifs

Un accident sur un réacteur nucléaire avec dépôt de radionucléides sur des surfaces urbaines pourrait présenter un danger d'irradiation externe pour les populations. Afin d'appréhender cerisque, et compte tenu du peu de données disponibles dans la littérature, il nous est apparu opportun de tester en laboratoire l'efficacité de techniques de décontamination sur des surfaces urbaines judicieusement choisies avant d'envisager une étude de faisabilité à plus grande échelle. L'originalité de ce travail a consisté à évaluer, par le biais d'expérimentations en milieu contrôlé, l'efficacité d'une pluie et de lavages avec des solutions agressives sur des tuiles en argile et du béton contaminés avec des aérosols de césium et de strontium. L'eau de pluie s'est révélée peu efficace pour éliminer les radionucléides, son action est d'autant plus faible que l'intensité de la pluie est élevée. Une plus grande efficacité a été obtenue après 2 h 30 de lavage avec la solution NH4Cl (0,1 mol l-1) appliquée directement après la contamination. L'activité résiduelle est alors de 90 % sur les tuiles et de 40 % sur le béton. Les résultats obtenus sont moyens pour le béton mais peu satisfaisants pour les tuiles et confirment, dans des conditions de dépôt accidentel, la difficulté de déplacer une telle contamination

Biopsychosocial contexts influence adult cognitive function concurrently and longitudinally

Background: Cognitive aging is a complex process that impacts human behavior. Identifying the factors that preserve cognitive functioning is a public health priority, given that 20% of the US population will be at least 65 years old in the next decade. Biopsychosocial determinants of cognitive decline across the lifespan are often examined as ecological factors that independently moderate cognitive aging, despite the known complexity surrounding these relationships. Objective: We aimed to address this gap by exploring the synergistic and simultaneous relationship between risk and protective factors on cognitive functioning. Method: Using the MIDUS study datasets, we examined the relationships among physiological markers, friendship quality, and global cognition functioning, concurrently and longitudinally over ten years. Our participants included 929 healthy (417 men, 512 women) adults (average age at Time 1: 54.6 ± 11.6 years). Exploratory analyses examining the effects of racial minority status were also conducted. Results: Cross-sectionally, age, and friendship quality moderated the relationship between vagally-mediated heart rate variability (vm-HRV) and cognition such that younger adults with greater friendship quality had a negative relationship between vm-HRV and cognitive performance; our unexpected finding suggests the heart-brain relationship is sensitive to the biopsychosocial environment. Longitudinally, higher IL-6 levels at Time 1 predicted poorer cognitive performance a decade later, but only among those with greater levels of friendship quality, especially for white-identifying individuals. Conclusions: The relationships among physiological risk factors, social protective factors and cognitive functioning appear to be temporally different during mid-adulthood. Given many of the whole sample findings were not replicated within the racial minority subgroup, we suggest that these relationships should be examined in a larger and more diverse racial minority sample to determine whether this study lacked the power necessary to detect a relationship or if the relationships are in fact different by racial minority sub-group. In addition, future research should overcome the study's reliance on healthy adults and self-report measures of friendship quality by including adults with pre-existing cognitive impairments, and employing more real-time measures of friendship quality, such as daily diary or ecological momentary assessment

Rétention de sels simples par une membrane chargée d'ultrafiltration à base d'alumine gamma

Une membrane d'ultrafiltration en alumine γ a été utilisée pour la filtration de différentes solutions salines. Les rétentions des différents sels ont été d'abord mesurées à l'aide de cette membrane puis les coefficients de réflexion σ et les perméabilités P pour chaque sel ont été déterminées. La rétention des sels peut être expliquée par un mécanisme d'exclusion de type Donnan

Fast and effective focused retrieval

Building an efficient and an effective search engine is a very challenging task. In this paper, we present the efficiency and effectiveness of our search engine at the INEX 2009 Efficiency and Ad Hoc Tracks. We have developed a simple and effective pruning method for fast query evaluation, and used a two-step process for Ad Hoc retrieval. The overall results from both tracks show that our search engine performs very competitively in terms of both efficiency and effectiveness