Territoires, Villes, Environnement & Société

BACKGROUND: The intestinal mucus layer plays a key role in the maintenance of host-microbiota homeostasis. To document the crosstalk between the host and microbiota, we used gnotobiotic models to study the influence of two major commensal bacteria, Bacteroides thetaiotaomicron and Faecalibacterium prausnitzii, on this intestinal mucus layer. B. thetaiotaomicron is known to use polysaccharides from mucus, but its effect on goblet cells has not been addressed so far. F. prausnitzii is of particular physiological importance because it can be considered as a sensor and a marker of human health. We determined whether B. thetaiotaomicron affected goblet cell differentiation, mucin synthesis and glycosylation in the colonic epithelium. We then investigated how F. prausnitzii influenced the colonic epithelial responses to B. thetaiotaomicron. RESULTS: B. thetaiotaomicron, an acetate producer, increased goblet cell differentiation, expression of mucus-related genes and the ratio of sialylated to sulfated mucins in mono-associated rats. B. thetaiotaomicron, therefore, stimulates the secretory lineage, favoring mucus production. When B. thetaiotaomicron was associated with F. prausnitzii, an acetate consumer and a butyrate producer, the effects on goblet cells and mucin glycosylation were diminished. F. prausnitzii, by attenuating the effects of B. thetaiotaomicron on mucus, may help the epithelium to maintain appropriate proportions of different cell types of the secretory lineage. Using a mucus-producing cell line, we showed that acetate up-regulated KLF4, a transcription factor involved in goblet cell differentiation. CONCLUSIONS: B. thetaiotaomicron and F. prausnitzii, which are metabolically complementary, modulate, in vivo, the intestinal mucus barrier by modifying goblet cells and mucin glycosylation. Our study reveals the importance of the balance between two main commensal bacteria in maintaining colonic epithelial homeostasis via their respective effects on mucus.

Point defects in Fe and dilute FeCu alloys are investigated by ab initio calculations based on density functional theory. The relaxed vacancy and interstitial and substitutional Cu atom formation energies are determined as well as some migration energies. The binding energies of various Cu containing defects believed to play an important role in the embrittlement of pressure vessel steels under radiation are calculated and discussed. The results are consistent with a Cu transport via a vacancy mechanism. The introduction of a Cu atom decreases the energy difference between the $〈110〉$ dumbbell and the $〈111〉$ dumbbell configurations, and should make the dumbbell rotation motion easier. The ab initio results are compared to the figures obtained with empirical interatomic potentials. The convergence of the results with the simulated system size is examined.

PURPOSE: While the health benefits of a high fruit and vegetable consumption are well known and considerable work has attempted to improve intakes, increasing evidence also recognises a distinction between fruit and vegetables, both in their impacts on health and in consumption patterns. Increasing work suggests health benefits from a high consumption specifically of vegetables, yet intakes remain low, and barriers to increasing intakes are prevalent making intervention difficult. A systematic review was undertaken to identify from the published literature all studies reporting an intervention to increase intakes of vegetables as a distinct food group. METHODS: Databases-PubMed, PsychInfo and Medline-were searched over all years of records until April 2015 using pre-specified terms. RESULTS: Our searches identified 77 studies, detailing 140 interventions, of which 133 (81 %) interventions were conducted in children. Interventions aimed to use or change hedonic factors, such as taste, liking and familiarity (n = 72), use or change environmental factors (n = 39), use or change cognitive factors (n = 19), or a combination of strategies (n = 10). Increased vegetable acceptance, selection and/or consumption were reported to some degree in 116 (83 %) interventions, but the majority of effects seem small and inconsistent. CONCLUSIONS: Greater percent success is currently found from environmental, educational and multi-component interventions, but publication bias is likely, and long-term effects and cost-effectiveness are rarely considered. A focus on long-term benefits and sustained behaviour change is required. Certain population groups are also noticeably absent from the current list of tried interventions.

Purpose The purpose of this paper is to understand Gen Zers’ tourism experiences and more specifically, through their tourist practices and their use of social networks. It also explores how Gen Zers apprehends the concept of sustainable tourism. Design/methodology/approach The authors used a qualitative research approach. The study protocol was conducted in two phases. First, the authors did six semi-directive interviews of young people born between 1995 and 2002. For the second stage of the research, the authors chose the narrative research technique by asking 34 students born between 1995 and 1997 to write a micro story from their travel experience. Findings Although it is often presented as a narcissistic generation, seeking to put forward their “selves”, for example by posting selfies, this study reveals that Generation Z seems to show a great modesty during their tourist experiences. The results also show that sustainable tourism is not a key concept for the young people interviewed. Research limitations/implications Thus, it would be useful to carry out more interviews and to extend the fields of analysis. While certain rules have been respected in the selection of young respondents, the sample does not necessarily reflect all the dimensions characterizing this complex young generation. Social implications We know that Generation Y has been exposed to social networks, often without a filter. The results show that Generation Z is much more suspicious and vigilant with regard to social networks and their use. Originality/value This research used an innovative method. It shows how multidimensional this generation is and opens up many ways of research.

A fashionable concept, resilience is now a must in both academic research and management. However, its polysemy nourishes many debates on its uses, heuristics and operational relevance. The purpose of this article is not to bring these debates to a close. Starting from a cross-disciplinary state of the art, we point out the incompatibilities between certain meanings and uses of the term. These inconsistencies raise theoretical issues, leading some researchers to reject the term for that matter, especially those outside the cindynics field. The analysis of the concept also brings out some methodological pitfalls. These are evident when attempting to translate theory into operational terms. Resilience is indeed seen as a promising response to recurrent difficulties in risk management. Nevertheless, it solves them only partially and produces new ones. Lastly, its implementation involves ethical and political risks. The injunction to resilience that seems to prevail internationally is in fact implying a number of moral and ideological assumptions which are not always clearly stated and remain serious issues.

Fuel cells are electrochemical devices that convert the chemical energy of a gaseous fuel directly into electricity. They are widely regarded as potential future stationary and mobile power sources. The response of a fuel-cell system depends on the air and hydrogen feed, flow and pressure regulation, and heat and water management. In this paper, the study is concentrated on the air subsystem that feeds the fuel-cell cathode with oxygen. Proceeding from a fourth-order model representing the air subsystem of a proton exchange membrane (PEM) fuel cell, a reduced third-order model is presented. Simulations show that the relative error caused by this reduction does not exceed 5%. Experimental validation has been done on a 33-kW PEM fuel cell, for both fourth- and reduced third-order models with less than 5% relative error. Additionally, a higher order sliding-mode supertwisting algorithm, with a well-known heuristic modification using variable gains, has been designed and validated experimentally to control a permanent-magnet synchronous motor that drives a volumetric compressor (double screw) designed to feed the 33-kW fuel cell with air.

Cet ouvrage présente de façon synthétique, en les recoupant par thèmes et approches, la plupart des travaux qui, depuis vingt ans, ont cherché à rendre compte des usages des technologies de communication, c'est-à-dire des objets, outils et dispositifs techniques permettant l'interaction à distance et une réciprocité dans la communication (téléphonie, internet, jeux en ligne). Mettant l'accent sur la mesure des changements que ces usages ont induits, il en expose les enjeux en termes économique, politique et social.

Defect-driven diffusion of impurities is the major phenomenon leading to formation of embrittling nanoscopic precipitates in irradiated reactor pressure vessel (RPV) steels. Diffusion depends strongly on the kinetic correlations that may lead to flux coupling between solute atoms and point defects. In this work, flux coupling phenomena such as solute drag by vacancies and radiation-induced segregation at defect sinks are systematically investigated for six bcc iron-based dilute binary alloys, containing Cr, Cu, Mn, Ni, P, and Si impurities, respectively. First, solute-vacancy interactions and migration energies are obtained by means of ab initio calculations; subsequently, self-consistent mean field theory is employed in order to determine the exact Onsager matrix of the alloys. This innovative multiscale approach provides a more complete treatment of the solute-defect interaction than previous multifrequency models. Solute drag is found to be a widespread phenomenon that occurs systematically in ferritic alloys and is enhanced at low temperatures (as for instance RPV operational temperature), as long as an attractive solute-vacancy interaction is present, and that the kinetic modeling of bcc alloys requires the extension of the interaction shell to the second-nearest neighbors. Drag occurs in all alloys except Fe(Cr); the transition from dragging to nondragging regime takes place for the other alloys around (Cu, Mn, Ni) or above (P, Si) the Curie temperature. As far as only the vacancy-mediated solute migration is concerned, Cr depletion at sinks is foreseen by the model, as opposed to the other impurities which are expected to enrich up to no less than 1000 K. The results of this study confirm the current interpretation of the hardening processes in ferritic-martensitic steels under irradiation.

The desire to improve the corrosion resistance of Zr cladding material for high burn-up has resulted in a general trend among fuel manufacturers to develop alloys with reduced levels of Sn. While commonly accepted, the reason for the improved corrosion performance observed for low-tin zirconium alloys in high-temperature aqueous environments remains unclear. High-energy synchrotron X-ray diffraction was used to characterize the oxides formed by autoclave exposure on Zr–Sn–Nb alloys with tin concentration ranging from 0.01 to 0.92 wt.%. The alloys studied included the commercial alloy ZIRLO® (ZIRLO® is a registered trademark of Westinghouse Electric Company LLC in the USA and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited.) and two variants of ZIRLO with significantly lower tin levels, referred to here as A-0.6Sn and A-0.0Sn. The nature of the oxide grown on tube samples from each alloy was investigated via cross-sectional scanning electron microscopy. Atom probe analysis of ZIRLO demonstrated that the tin present in the alloy passes into the oxide as it forms, with no significant difference in the Sn/Zr ratio between the two. Synchrotron X-ray diffraction measurements on the oxides formed on each alloy revealed that the monoclinic and tetragonal oxide phases display highly compressive in-plane residual stresses with the magnitudes dependent on the phase and alloy. The amount of tetragonal phase present and, more importantly, the level of tetragonal-to-monoclinic phase transformation both decrease with decreasing tin levels, suggesting that tin is a tetragonal oxide phase stabilizing element. It is proposed that in Zr–Nb–Sn alloys with low Sn, the tetragonal phase is mainly stabilized by very small grain size and therefore remains stable throughout the corrosion process. In contrast, alloys with higher tin levels can in addition grow larger, stress stabilized, tetragonal grains that become unstable as the corrosion front continues to grow further inwards and stresses in the existing oxide relax.

Abstract Typical applications of solvent-free conditions and microwave activation are described. Non-purely thermal specific effects are evidenced and discussed in terms of reaction medium and mechanisms, taking into account the variations in polarity of the systems.

We present a first-principles study of the electronic properties of CuIn(S,Se){2} (CIS) using state-of-the-art self-consistent GW and hybrid functionals. The calculated band gap depends strongly on the anion displacement u, an internal structural parameter that measures lattice distortion. This contrasts with the observed stability of the band gap of CIS solar panels under operating conditions, where a relatively large dispersion of values for u occurs. We solve this apparent paradox considering the coupled effect on the band gap of copper vacancies and lattice distortions. The correct treatment of d electrons in these materials requires going beyond density functional theory, and GW self-consistency is critical to evaluate the quasiparticle gap and the valence band maximum.

Wind and solar generation may consequently be difficult to predict over some time scales. Large penetrations of variable generation (VG) lead to increases in the variability and uncertainty in the system's generation output, driving a need for greater flexibility. This flexibility will need to come either from flexible generation technologies or from alternative sources of flexibility such as flexible demand and storage. This article will discuss the additional flexibility needs introduced by variable generation from wind and solar power and will describe general approaches to analyzing the need for and provision of additional flexibility in the power system in both the operational and planning time frames.

In this work, an industrially produced polymer electrolyte based on the poly(ethylene oxide) PEO-LiTFSI is studied. The evolution of the impedance spectra of symmetric cells Li/PEO-LiTFSI/Li with the aging time at 90°C is presented. The variation of impedance spectra as a function of temperature and electrolyte geometry is also shown, especially the low frequency part (up to 0.5 mHz). An equivalent electrical circuit is proposed to describe the whole spectra. The major contributions to the impedance of this interface are identified. From the low frequency contribution, the salt diffusion coefficient is determined. Finally, we use a simple model of the surface layer to gain some insight into its properties. © 2003 The Electrochemical Society. All rights reserved.

Novel species of fungi described in this study include those from various countries as follows: Australia , Austroboletus asper on soil, Cylindromonium alloxyli on leaves of Alloxylon pinnatum, Davidhawksworthia quintiniae on leaves of Quintinia sieberi, Exophiala prostantherae on leaves of Prostanthera sp., Lactifluus lactiglaucus on soil, Linteromyces quintiniae (incl. Linteromyces gen. nov.) on leaves of Quintinia sieberi , Lophotrichus medusoides from stem tissue of Citrus garrawayi , Mycena pulchra on soil, Neocalonectria tristaniopsidis (incl. Neocalonectria gen. nov.)and Xyladictyochaeta tristaniopsidis on leaves of Tristaniopsis collina, Parasarocladium tasmanniae on leaves of Tasmannia insipida , Phytophthora aquae-cooljarloo from pond water, Serendipita whamiae as endophyte from roots of Eriochilus cucullatus , Veloboletus limbatus (incl. Veloboletus gen. nov.)onsoil. Austria , Cortinarius glaucoelotus onsoil. Bulgaria , Suhomyces rilaensis from the gut of Bolitophagus interruptus found on a Polyporus sp. Canada , Cantharellus betularum among leaf litter of Betula , Penicillium saanichii from house dust. Chile , Circinella lampensis on soil, Exophiala embothrii from rhizosphere of Embothrium coccineum . China, Colletotrichum cycadis on leaves of Cycas revoluta . Croatia , Phialocephala melitaea on fallen branch of Pinus halepensis . Czech Republic , Geoglossum jirinae on soil, Pyrenochaetopsis rajhradensis from dead wood of Buxus sempervirens. Dominican Republic , Amanita domingensis on litter of deciduous wood, Melanoleuca dominicana on forest litter. France , Crinipellis nigrolamellata (Martinique) on leaves of Pisonia fragrans , Talaromyces pulveris from bore dust of Xestobium rufovillosum infesting floorboards. French Guiana , Hypoxylon hepaticolor on dead corticated branch. Great Britain , Inocybe ionolepis on soil. India , Cortinarius indopurpurascens among leaf litter of Quercus leucotrichophora . Iran , Pseudopyricularia javanii on infected leaves of Cyperus sp., Xenomonodictys iranica (incl. Xenomonodictys gen. nov.) on wood of Fagus orientalis . Italy , Penicillium vallebormidaense from compost. Namibia , Alternaria mirabibensis on plant litter, Curvularia moringae and Moringomyces phantasmae (incl. Moringomyces gen. nov.) on leaves and flowers of Moringa ovalifolia, Gobabebomyces vachelliae (incl. Gobabebomyces gen. nov.) on leaves of Vachellia erioloba, Preussia procaviae on dung of Procavia capensis . Pakistan , Russula shawarensis from soil on forest floor. Russia , Cyberlindnera dauci from Daucus carota . South Africa , Acremonium behniae on leaves of Behnia reticulata, Dothiora aloidendri and Hantamomyces aloidendri (incl. Hantamomyces gen. nov.) on leaves of Aloidendron dichotomum , Endoconidioma euphorbiae on leaves of Euphorbia mauritanica , Eucasphaeria proteae on leaves of Protea neriifolia , Exophiala mali from inner fruit tissue of Malus sp., Graminopassalora geissorhizae on leaves of Geissorhiza splendidissima , Neocamarosporium leipoldtiae on leaves of Leipoldtia schultzii , Neocladosporium osteospermi on leaf spots of Osteospermum moniliferum , Neometulocladosporiella seifertii on leaves of Combretum caffrum , Paramyrothecium pituitipietianum on stems of Grielum humifusum , Phytopythium paucipapillatum from roots of Vitis sp., Stemphylium carpobroti and Verrucocladosporium carpobroti on leaves of Carpobrotus quadrifolius , Suttonomyces cephalophylli on leaves of Cephalophyllum pilansii . Sweden , Coprinopsis rubra on cow dung, Elaphomyces nemoreus fromdeciduouswoodlands. Spain , Polyscytalum pini-canariensis on needles of Pinus canariensis , Pseudosubramaniomyces septatus from stream sediment, Tuber lusitanicum on soil under Quercus suber . Thailand , Tolypocladium flavonigrum on Elaphomyces sp. USA , Chaetothyrina spondiadis on fruits of Spondias mombin, Gymnascella minnisii from bat guano, Juncomyces patwiniorum on culms of Juncus effusus , Moelleriella puertoricoensis on scale insect, Neodothiora populina (incl. Neodothiora gen. nov.) on stem cankers of Populus tremuloides , Pseudogymnoascus palmeri fromcavesediment. Vietnam , Cyphellophora vietnamensis on leaf litter, Tylopilus subotsuensis on soil in montane evergreen broadleaf forest. Morphological and culture characteristics are supported by DNA barcodes.

A novel category of major intrinsic proteins which share weak similarities with previously identified aquaporin subfamilies was recently identified in land plants, and named X (for unrecognized) intrinsic proteins (XIPs). Because XIPs are still ranked as uncharacterized proteins, their further molecular characterization is required. Herein, a systematic fine-scale analysis of XIP sequences found in flowering plant databases revealed that XIPs are found in at least five groups. The phylogenetic relationship of these five groups with the phylogenetic organization of angiosperms revealed an original pattern of evolution for the XIP subfamily through distinct angiosperm taxon-specific clades. Of all flowering plant having XIPs, the genus Populus encompasses the broadest panel and the highest polymorphism of XIP isoforms, with nine PtXIP sequences distributed within three XIP groups. Comprehensive PtXIP gene expression patterns showed that only two isoforms (PtXIP2;1 and PtXIP3;2) were transcribed in vegetative tissues. However, their patterns are contrasted, PtXIP2;1 was ubiquitously accumulated whereas PtXIP3;2 was predominantly detected in wood and to a lesser extent in roots. Furthermore, only PtXIP2;1 exhibited a differential expression in leaves and stems of drought-, salicylic acid-, or wounding-challenged plants. Unexpectedly, the PtXIPs displayed different abilities to alter water transport upon expression in Xenopus laevis oocytes. PtXIP2;1 and PtXIP3;3 transported water while other PtXIPs did not.

Periodic density functional theory (DFT) calculations using plane-wave basis sets were performed in order to study the bulk of nickel ferrite NiFe2O4. The local spin density approximation (LSDA) and the generalized gradient approximation (GGA) formalism were used, and it appeared that the LSDA failed to describe the magnetic structure of this compound. However, the GGA formalism gave reliable results in good agreement with experimental data for the lattice parameters, the electronic properties and the bulk modulus. In addition, the calculated density of states of the metallic species d block as well as their local magnetic moments were correlated to the crystal-field theory. Then, a charge deformation map was computed and, as expected from the electronegativity scale, the electron excess is localized around oxygen atoms along the bond axes. The formation energies of metallic vacancies are in good agreement with the inverse spinel structure experimentally observed.

From September 1992 to January 1994, we evaluated the use of the CEPRATE SC stem cell concentrator (CellPro, Inc, Bothell, WA) to select CD34+ cells from the bone marrow (BM) of 25 patients with non-Hodgkin's lymphoma in complete remission. This system uses the biotinylated 12.8 IgM MoAb to select CD34+ cells. Cells are retained on an avidin column and detached by agitation. Fifteen patients have been transplanted with the CD34+ purified fraction. The CD34+ purified fraction of the 25 processed BMs contained a median of 0.54% of the original nucleated cells in a volume of 5 to 10 mL. The median concentration of CD34+ cells was 49% (range, 12% to 80%), and the median enrichment of CD34+ cells was 33-fold (range, 9- to 85-fold). This selected CD34+ fraction retained 60% (range, 15% to 95%) of late granulocyte-macrophage colony-forming units (CFU-GM), 55% (range, 12% to 99%) of early CFU-GM, and 31% (range, 2% to 100%) erythroid burst-forming units (BFU-E) corresponding to median enrichments of 22-fold (range, 1- to 71-fold), 19-fold (range, 2- to 58-fold), and 14-fold (range, 2- to 200-fold), respectively. There was a correlation between immune phenotypes and progenitor cells. In the initial buffy-coat fractions, the percentage of CD34+ cells was correlated to the cloning efficiency of both late CFU-GM (P < .05) and early CFU-GM (P < .001). In the final selected fraction, there was a correlation between the percentage of CD34+/CD33- and the cloning efficiency of early CFU-GM (P < .05) and between the percentage of CD34+/CD33+ and the cloning efficiency of late CFU-GM (P < .05). Lymphoma cells positive for t(14; 18) were found by polymerase chain reaction in 9 of 14 buffy coats tested before CD34+ cell purification. In 8 cases, the CD34(+)-selected fraction was found to be negative, and the CD34- fraction was found to be positive. After cryopreservation, the recoveries of progenitor cells in the CD34(+)-purified fraction were 79% for late CFU-GM, 71% for early CFU-GM, and 73% for BFU-E. The 15 patients transplanted with the concentrated CD34+ fraction received a median dose of 1 x 10(6) CD34+ cells/kg (range, 0.3 to 2.96) and 10.62 x 10(4) early CFU-GM/kg (range, 0.92 to 25.55). Median days to recovery to 0.5 x 10(9)/L neutrophils and 50 x 10(9)/L platelets were days 15 (range, 10 to 33) and 23 (range, 11 to 68), respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Zirconium alloys are currently used in nuclear power plants where they are susceptible to hydrogen pick-up. Hydride precipitation may occur when the hydrogen solubility limit is reached. Various Zr hydride phases, gamma, delta and epsilon have been identified since the 1950s. Combining electron precession microdiffraction, electron energy loss spectroscopy and ab initio electronic calculations, a new Zr hydride named zeta has been identified and characterized. It belongs to the trigonal crystal system with space group P3 m1 and it is fully coherent with the alphaZr matrix.

Small interstitial-type defects in iron with complex structures and very low mobilities are revealed by molecular dynamics simulations. The stability of these defect clusters formed by nonparallel {110} dumbbells is confirmed by density functional theory calculations, and it is shown to increase with increasing temperature due to large vibrational formation entropies. This new family of defects provides an explanation for the low mobility of clusters needed to account for experimental observations of microstructure evolution under irradiation at variance with the fast migration obtained from previous atomistic simulations for conventional self-interstitial clusters.

In the current context of the ban on fossil fuel vehicles (diesel and petrol) adopted by several European cities, the question arises of the development of the infrastructure for the distribution of alternative energies, namely hydrogen (for fuel cell electric vehicles) and electricity (for battery electric vehicles). First, we compare the main advantages/constraints of the two alternative propulsion modes for the user. The main advantages of hydrogen vehicles are autonomy and fast recharging. The main advantages of battery-powered vehicles are the lower price and the wide availability of the electricity grid. We then review the existing studies on the deployment of new hydrogen distribution networks and compare the deployment costs of hydrogen and electricity distribution networks. Finally, we conclude with some personal conclusions on the benefits of developing both modes and ideas for future studies on the subject.