439 research outputs found
Oxygen reduction at the silver/hydroxide-exchange membrane interface
A solid-state cell is used to study the electrocatalysis of oxygen reduction at the silver/hydroxide-exchange membrane interface. The catalyst/membrane interface exhibits improved performance in comparison to a catalyst/aqueous sodium hydroxide interface. Surprisingly, the half-wave potential for oxygen reduction is shown to shift 185 mV higher at the silver/hydroxide-exchange membrane interface than for the silver/aqueous hydroxide solution interface, and the exchange current density is significantly higher at 1.02 × 10−6 A m−2. On a cost per performance basis, silver electrocatalysts in a hydroxide-exchange membrane fuel cell may provide better performance than platinum in a proton-exchange membrane fuel cell. Keywords: Oxygen reduction reaction, Electrocatalyst, Alkaline membrane, Solid-state cell, Silve
Synthesis, structure and conductivity of sulfate and phosphate doped SrCoO3
In this paper we report the successful incorporation of sulfate and phosphate into SrCoO3 leading to a change from a 2H– to a 3C–perovskite polymorph. Structural characterization by neutron diffraction showed extra weak peaks related to oxygen vacancy ordering, and these could be indexed on an expanded tetragonal cell, containing two inequivalent Co sites, similar to previously reported for Sb doped SrCoO3. Conductivity measurements on the doped systems showed a large enhancement compared to the undoped hexagonal system, consistent with corner–sharing of CoO6 octahedra for the former. Further work on the doped samples shows, however, that they are metastable, transforming back to the hexagonal cell on annealing at intermediate temperatures. The incorporation of Fe was shown, however, to improve the stability at intermediate temperatures, and these co–doped phases also showed high conductivities
Internal-quantum-state engineering using magnetic fields
We present a general, semi-classical theory describing the interaction of an atom with an internal state consisting of a number of degenerate energy levels with static and oscillating magnetic fields. This general theory is applied to the 3P2 metastable energy level of neon to determine the dynamics of the populations and coherences that are formed due to the interaction. Through these calculations we demonstrate how the interaction may be used for the internal state preparation of an atom
Subtle Sensing:Detecting Differences in the Flexibility of Virtually Simulated Molecular Objects
During VR demos we have performed over last few years, many participants (in
the absence of any haptic feedback) have commented on their perceived ability
to 'feel' differences between simulated molecular objects. The mechanisms for
such 'feeling' are not entirely clear: observing from outside VR, one can see
that there is nothing physical for participants to 'feel'. Here we outline
exploratory user studies designed to evaluate the extent to which participants
can distinguish quantitative differences in the flexibility of VR-simulated
molecular objects. The results suggest that an individual's capacity to detect
differences in molecular flexibility is enhanced when they can interact with
and manipulate the molecules, as opposed to merely observing the same
interaction. Building on these results, we intend to carry out further studies
investigating humans' ability to sense quantitative properties of VR
simulations without haptic technology
Clinical utility of magnetocardiography in cardiology for the detection of myocardial ischemia
It is a review article. The abstract is not availabl
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