2,174 research outputs found

    Oxygen surface exchange kinetics of erbia-stabilized bismuth oxide

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    The surface oxygen exchange kinetics of bismuth\ud oxide stabilized with 25 mol% erbia (BE25) has been studied\ud in the temperature and pO2 ranges 773–1,023 K and 0.1–\ud 0.95 atm, respectively, using pulse-response 18O–16O isotope\ud exchange measurements. The results indicate that BE25\ud exhibits a comparatively high exchange rate, which is rate\ud determined by the dissociative adsorption of oxygen. Defect\ud chemical considerations and the observed pO2\ud 1=2 dependence\ud of the rate of dissociative oxygen adsorption suggest\ud electron transfer to intermediate superoxide ions as the rate\ud determining step in surface oxygen exchange on BE2

    Changing paradigms of renal replacement therapy in chronic kidney disease patients: ultrapure dialysis fluid and high-efficiency hemodiafiltration for all?

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    Ultrapurity of dialysis fluid is important for the biocompatibility of renal replacement therapy systems. Penne and collaborators have assessed the microbiological quality of water and dialysis fluid in dialysis facilities. No side effects were noted in 97 patients who received 11,258 online hemodiafiltration sessions. This study confirms that ultrapure water and dialysis fluid may be easily produced and used for online hemodiafiltration

    Influence of storage conditions on survival and sowing value of seed of tropical pasture grasses. 1. Longevity

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    To find ways of improving the sowing value of seed of tropical pasture grasses through attention to the storage environment used commercially, fresh seed lots of Panicum maximum, Brachiaria decumbens, Brachiaria humidicola, Setaria sphacelata and Chloris gayana were stored under different conditions and sampled periodically for laboratory, greenhouse and field testing. Comparisons were made between seed lots stored in bags of open weave in a cool-room at 10°C and 50% RH and in an open store-room at ambient temperature. Seed lots of P. maximum in moisture-proof packets at 5 different moisture contents between 7.3 and 12.9% were compared. One seed lot was also freezer-stored at −12°C. Part 1 reports their viability and dormancy loss. Viability loss of seed in woven bags in open storage was complete within 3 years while barely detectable in similar cool-stored seed. Rates of loss in sealed packets increased with moisture content at ambient temperatures. They were much higher in seed in woven bags at comparable average moisture contents, an effect attributed largely to spatial moisture content gradients. Cool storage temperatures and low seed moisture contents appeared to prolong dormancy, while freezer storage retained and even intensified it

    Polvo y lodo : Chalco

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    The Vacuum Chamber of the GANIL SSC

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    http://accelconf.web.cern.ch/AccelConf/c78/papers/a-14.pdfInternational audienc

    Infinite N phase transitions in continuum Wilson loop operators

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    We define smoothed Wilson loop operators on a four dimensional lattice and check numerically that they have a finite and nontrivial continuum limit. The continuum operators maintain their character as unitary matrices and undergo a phase transition at infinite N reflected by the eigenvalue distribution closing a gap in its spectrum when the defining smooth loop is dilated from a small size to a large one. If this large N phase transition belongs to a solvable universality class one might be able to calculate analytically the string tension in terms of the perturbative Lambda-parameter. This would be achieved by matching instanton results for small loops to the relevant large-N-universal function which, in turn, would be matched for large loops to an effective string theory. Similarities between our findings and known analytical results in two dimensional space-time indicate that the phase transitions we found only affect the eigenvalue distribution, but the traces of finite powers of the Wilson loop operators stay smooth under scaling.Comment: 31 pages, 9 figures, typos and references corrected, minor clarifications adde
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