Effect of geometrical conditions on the mass-transfer parameters near a polarized liquid metallic electrode: I. Electrode size

The behavior of liquid metallic electrode-chloride melt systems is studied as a function of the electrode size. The precipitation of lead on a solid substrate and the effect of the liquid electrode diameter on the mass-transfer intensity are investigated in the Pb-NaCl-KCl (1: 1)-PbCl₂ system in the circulation cell and laminar flow regimes.     

<Superscript>99</Superscript>Tc NMR Spectroscopy

⁹⁹Tc NMR data for Tc compounds in various oxidation states are summarized.__________Translated from Radiokhimiya, Vol. 47, No. 4, 2005, pp. 291–304.Original Russian Text Copyright © 2005 by Mikhalev.     

Parameters of free radical oxidation in blood plasma of women from the Alta? region

The minimum inhibitory concentrations of 39 Helicobacter pylori strains against antibiotics (ampicillin, tetracycline, metronidazole), colloidal bismuth subcitrate and proton pump inhibitors were assessed by the agar dilution method. 20.5% of the strains were metronidazole resistent. The comparison of the bactericidal action of omeprazole and lansoprazole in a killing curve assay showed a dose-dependent reduction of viable bacteria after 24 h, lansoprazole being more effective than omeprazole. Under varying pH conditions, the antibacterial activity of lansoprazole was limited to a pH range of 6-7, reducing bacterial numbers up to 4 logarithmical steps within 24 h.     

Mechanochemical preparation,sintering aids and hybrid microwave sintering in the proton conductor Sr0.02La0.98Nb1-xVxO4-δ, x = 0, 0.15

Mechanochemical preparation of Sr_0.02La_0.98Nb_1-xV_xO_4-δ was demonstrated for values of x = 0 and 0.15. Crystallinity could be improved by calcining at 1073 K. On cooling, the high temperature scheelite phase was retained to room temperature. Several novel sintering additives for LaNbO₄ materials have been tested. The most successful were Cu₃Nb₂O₈ and CuV₂O₆, which reduced the temperature of maximum shrinkage rate to temperatures ∼1173 K. The additive CuV₂O₆ was shown to increase densification and promote grain growth. A mechanosynthesised sample of Sr_0.02La_0.98Nb_0.85V_0.15O_4-δ + 2 mol% CuV₂O₆ could be densified to ∼ 90% that of the theoretical by hybrid microwave sintering at 1168 K for 5 min. The scheelite phase in this material was retained to room temperature, against the normal thermodynamic tendency. Impedance spectroscopy in wet and dry, nitrogen and oxygen atmospheres suggested that the bulk conductivity of this material is unaffected by the sintering aid, whereas the grain boundary conductivity was impaired and exhibited n-type conductivity behaviour, characteristic of the additive. The concentration of this promising additive should be reduced in further work.     

Production of Biochar and Other High Value-Added Products from Biomass by Wet Torrefaction in Fluidized Bed in Superheated Steam Environment

Chemical and Petroleum Engineering - The advantages of wet torrefaction of biomass by superheated steam in fluidized bed over conventional hydrothermal carbonization method are confirmed. The...     

Toward improved chemical stability of yttrium-doped barium cerate by the introduction of nickel oxide

In this work, we demonstrate that the introduction of a small amount of NiO (1.8 wt%) to the proton-conducting perovskite yttrium-doped barium (BaCe_0.9Y_0.1O_3−δ, BCY10) can radically improve its chemical stability, even in conditions of very high carbon dioxide partial pressure (p_O2 = 1 atm) and wet conditions (p_H2O = 0.033 atm). To this end, we test sets of unmodified and NiO-modified BCY samples sintered at different temperatures to achieve different grain sizes. Long-term stability measurements up to 720 h at 400°C, under these conditions, reveal a noticeable drop in conductivity for the unmodified samples, scaling with decreasing grain size, due to the formation of barium carbonate. Conversely, the NiO-modified samples show no apparent degradation, with a stable conductivity performance retained over 720 h, irrespective of grain sizes. We tentatively attribute this unusual behavior to the increased chemical resistance of the perovskite phase due to an increase in the a_NiO/a_BaO activity ratio at the bulk surfaces, which can prevent surface attack. Such an effect is supported by an observed increase in the Schottky barrier height, revealing a change in the specific grain boundary properties of the NiO-modified samples. Conductivity measurements in wet O₂ (p_H2O = 0.033 atm) underscore that both the bulk and grain boundary terms of the conductivity of the NiO-modified sample, sintered at 1350°C, are competitive with the unmodified BCY sample, sintered at 1450°C, even at temperatures as low as 400°C. The results here reported, thus, unlock a different perspective for these transition metal additives, to improve the chemical resistance of proton-conducting ceramics perovskites.