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Weak Interaction of Oxygen with Refractory Carbides
No full textThe Electrochemical Soc., (P.Y. Hou, M.J. McNallan, R. Otra, E.J. Opila, D.A. Shores, Eds
The role of sintering time on reversibility of Ni(s)-NiO(s) electrodes for high-temperature solid oxide-electrolyte galvanic cells
No full textThe reversibility of solid-electrolyte galvanic cells such as, Mo|Ni(s)-NiO(s)|CSZ|Fe(s)-Fe1-δO(s)|Mo, (CSZ = CaO-contg. ZrO2) was studied with respect to the sintering time of the active powders. Pellets from short (7 h) and long (14 h) sintering times were prepd. and assembled to give the above cells. Each of them was thermally cycled and only the cells contg. Ni(s)-NiO(s) electrodes prepd. with a long sintering time gave emf. vs. T curves which were independent of cycle. These values agreed closely with the literature. For the cell reaction, NiO(s) + (1 - δ)Fe(s) = Ni(s) + Fe1-δO(s), ΔG = -(27.85 ± 0.06) - (0.02157 ± 0.00004)T kJ mol-1 at 977-1350 K. To check the electrochem. reversibility, cyclic voltammetry was also used. On the basis of these results and of SEM anal. of the electrode pellets, a mechanism is proposed whereby only at long sintering time would a triple phase contact at the electrode/electrolyte interface be produced
Conductivity of commercial zirconia electrolytes. II. n-Type conductivity of 15 m/o CSZ and 7.5 m/o MSZ at oxygen pressures of solid nickel-solid nickel oxide mixture
No full textThe n-type cond. of the com. 7.5 m/o MgO-stabilized ZrO2 and 15 m/o CaO-stabilized ZrO2 electrolytes was measured at O pressures of the Ni(s)-NiO(s) mixt. at 1073-1423 K by using the blocking electrode technique. The exptl. values of the activation energies were, resp., 1.58 and 1.38 eV for CaO-stabilized and MgO-stabilized ZrO2. The O ion transport no. was also measured as function of temp. and its value at 1273 K was 91%. The significance of the activation energy and PO2 dependence of the partial cond. in the particular exptl. conditions was emphasized
Conductivity of commercial zirconia electrolytes. I. Ionic and n-type conductivities of 15 m/o CSZ at oxygen pressures of solid chromium-solid chromium oxide mixture
No full textThe total and n-type conductivities of com. 15 m/o CaO-stabilized ZrO2 electrolyte were measured. The ionic and n-cond. activation energies are reported at 1195-1917 K as is the n-type cond. dependence on the equil. O partial pressure of the Cr(s)-Cr2O3(s) mixt. electrodes. Values of conduction were detd. and a chronoamperometric technique to measure it is reported. The physicochem. behavior of the Cr(s)-Cr2O3(s) mixt. deriving from certain anomalies obsd. in the cond. trends at the highest temp. values is considered
Some evidence on the instability of a chromium-chromium(III) oxide electrode in electrochemical oxygen sensors at steelmaking temperatures
No full textAnomalies were obsd. in measurements of emf. and elec. cond. measurements of solid oxide electrolyte cells involving Cr(s)-Cr2O3(s) electrodes. Transformation in the system at ∼1653 K explains the anomalies mentioned above on the basis of measured temp. dependence of emf. and total and electronic conductivities of the cells
Thermodynamics of the YAl-YAl2 system
No full textThe emf method using solid-slate galvanic cells based on a CaF2 single crystal as electrolyte has been used to investigate the thermodynamics of the intermetallic couple YAl-YAl2, These represent two out of the five intermetallic compounds shown in the Y-Al phase diagram. Two kinds of cells were studied:
(-)Pt/Y, YF3/CaF(2)s.c./YAl, YAl2, YF3/Pt(+) and (-)Pt/YAl, YAl2, CaAlF5, CaF2/CaF(2)s.c./Fe(Al, a(+)), CaAlF5; CaF2/Pt(+)
The cell reactions expected are, respectively, 2YAl (s) = YAl2 (s) + Y (s) and YAl (s) + Al (1, s) = YAl2 (s). The standard thermodynamic quantities Delta G degrees, Delta H degrees and Delta S degrees have been measured as a function of temperature for both the reactions. The Delta(f)H degrees(298) of YAl has also been derived by selecting from the literature the best value of Delta(f)H degrees(298) for YAl2. The value to assign to the formation of YAl have been found equal to: Delta(f)H degrees(298) = -107 +/- 6 k/J.mol. Moreover, Delta(f)S degrees(298) = 2 +/- 5 kJ/mol and Delta(f)G degrees(T) (-100 +/- 5) + (1.8 +/- 0.5)10(-2) T kJ/mol have been estimated in the temperature range from 792 to 1007 K. (C) 2000 Elsevier Science Ltd. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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