Asymmetrical thin membranes of SrCe
0.95Y
0.05O
3−
δ
(SCY) were prepared by a conventional and cost-effective dry pressing method. The substrate consisted of SCY, NiO and soluble starch (SS), and the ...top layer was the SCY. NiO was used as a pore former and soluble starch was used to control the shrinkage of the substrate to match that of the top layer. Crack-free asymmetrical thin membranes with thicknesses of about 50
μm and grain sizes of 5–10
μm were successfully pressed on to the substrates. Hydrogen permeation fluxes (
J
H
2
) of these thin membranes were measured under different operating conditions. At 950
°C,
J
H
2
of the 50
μm SCY asymmetrical membrane towards a mixture of 80% H
2/He was as high as 7.6
×
10
−8
mol/cm
2
s, which was about 7 times higher than that of the symmetrical membranes with a thickness of about 620
μm. The hydrogen permeation properties of SCY asymmetrical membranes were investigated and activation energies for hydrogen permeation fluxes were calculated. The slope of the relationship between the hydrogen permeation fluxes and the thickness of the membranes was −0.72, indicating that permeation in SCY asymmetric membranes was controlled by both bulk diffusion and surface reaction in the range investigated.
The hydrogen permeability of SrCe
0.95Eu
0.05O
3−
δ
and SrCe
0.95Sm
0.05O
3−
δ
was studied as a function of temperature, hydrogen partial pressure (
P
H
2
) gradient, and water vapor partial pressure ...(
P
H
2O
) gradient. Under a 100% dry hydrogen condition at 1123 K, the hydrogen permeation rates of dense membranes (1.72 mm thick) are ≈3.19×10
−9 mol/cm
2 s for SrCe
0.95Eu
0.05O
3−
δ
and 2.33×10
−9 mol/cm
2 s for SrCe
0.95Sm
0.05O
3−
δ
. Under wet hydrogen conditions at 1123 K, the hydrogen permeation rates are ≈2.89×10
−9 and 1.21×10
−9 mol/cm
2 s, respectively, for the same materials. The dopant dependence of hydrogen permeability is explained in terms of the ionization potential of the dopant. Electronic conductivity was calculated from hydrogen permeation fluxes; activation energies for electron conduction under both dry and wet conditions were also calculated. The
P
H
2O
dependence of electronic conductivity and hydrogen permeability is discussed.
The University Computing Centre (SRCE) established its presence on Internet based social networks in November 2009, namely on Facebook. Soon after, SRCE become present on Twitter, Google+, YouTube, ...LinkedIn and foursquare. Maintaining the presence and communication on social networks was initially one of the activities carried out by the SRCE Helpdesk service. However, as a result of the growing workload and responsibilities of the Helpdesk, a new service was established only for activities related to social networks. This paper discuses the communication strategy used by SRCE on social networks. The authors examined different web based tools and services to gather information about Internet users who follow SRCE's activities on different social network. A data analysis shows that the initial goals SRCE set in 2009 related to its communication strategy on social networks have been fulfilled. This data will also be used as a starting point for reconsideration of the existing communication strategy. With the emergence of new popular social networks there might be a need for expansion.
Mixed proton–hole conducting ceramic, SrCe
0.95Yb
0.05O
3−
α
(SCYb), hollow fibre membranes have been prepared using a combined immersion-induced phase inversion and sintering technique. Two ...different sintering routes have been adopted in studying the effect of sintering temperatures on gas-tight properties and mechanical strength of the prepared membranes. By employing longer time of heat treatment after thermolysis (i.e. removal of organic binders and additives at 600
°C), the final sintering temperature for preparation of the gas-tight SCYb hollow fibre membranes can be reduced. In addition, mechanical strength of the sintered membrane is found to be remarkably improved. The performance of the prepared SCYb hollow fibre membrane in terms of hydrogen permeation (proton conduction) has also been investigated experimentally.
A high-resolution method has been developed for the determination of localized values of interfacial reaction rate and mass transfer coefficient in aqueous solution. Scanning electron microscopy has ...been successfully applied to this problem through the measurement of electroplated film thickness formed under limiting current conditions. The method involves the calculation of local values of reaction rate via Faraday's laws and subsequent conversion of the data to absolute values of mass transfer coefficient. The technique has been verified in an undisturbed, turbulent flow regime (rotating cylinder electrode) through the use of Sherwood group dimensionless analysis. The resulting relationship shows comparable accuracy relative to electrochemical measurements. Favourable comparison has also been made with the generally accepted rotating cylinder correlation of Eisenberg, Tobias and Wilke. Differential rates of mass transfer to a single surface under conditions of disturbed flow have also been examined at a high spatial resolution using the stepped rotating cylinder electrode geometry. In this case, reaction rates have been measured as a function of circumferential distance within a recirculation zone situated immediately downstream of a backward-facing step.
The electronic structure of protonic conductor SrCe1-xYxO3-delta (x=,0.05) has been studied by resonant-photoemission spectroscopy (RPES) and X-ray absorption spectroscopy (XAS) in the soft-X-ray ...region. The RPES spectra exhibit that the O 2p state strongly hybridizes with Ce 4f state in the valence band. The valence band consists of the mixed-valent states of the 4f0 (Ce4+) and 4f1L (Ce3+) configurations. The XAS spectra in the band gap energy region show a hole state at the top of the valence band and an acceptor-induced level just above the Fermi level (EF). The energy position of the hole state accords with that of the Ce3+ state. The energy separation between the hole state and EF is in good agreement with the activation energy.
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