Oxygen reduction behavior of rutile-type iridium oxide in sulfuric acid solution

ArticleELECTROCHIMICA ACTA. 54(2):566-573 (2008)journal articl

An Examination of the Oxygen Reduction Reaction on RuO2-based Oxide Coatings Formed on Titanium Substrates

The RuO2-based electrocatalysts were prepared by using a dip-coating method on Ti plate substrates at 400 degrees C. The catalytic activity of the oxide-coated electrodes for the oxygen reduction reaction (ORR) was evaluated by cyclic voltammetry in 0.5 M H2SO4 at 60 degrees C in a stationary state. The examination was focused on the enhancement of the catalytic activity in the reaction by the enlargement of the surface area of the RuO2 coating with the help of lanthunum. The onset potential for the ORR, EORR-0, of the RuO2/Ti electrode showed that the highest value was 0.84 V vs. RHE.ArticleCatalysis Today. 146(1-2):248-252. (2009)journal articl

Studies of the 1^{1}S0_{0}--3^3P0_0 transition in atomic ytterbium for optical clocks and qubit arrays

We report an observation of the weak $6^{1}$S$_{0}$-$6^3$P$_0$ transition in $^{171,173}$Yb as an important step to establish Yb as a primary candidate for future optical frequency standards, and to open up a new approach for qubits using the $^{1}$S$_{0}$ and $^3$P$_0$ states of Yb atoms in an optical lattice.Comment: 5 pages, 3 figure

Accessing the dynamics of large many-particle systems using Stochastic Series Expansion

The Stochastic Series Expansion method (SSE) is a Quantum Monte Carlo (QMC) technique working directly in the imaginary time continuum and thus avoiding "Trotter discretization" errors. Using a non-local "operator-loop update" it allows treating large quantum mechanical systems of many thousand sites. In this paper we first give a comprehensive review on SSE and present benchmark calculations of SSE's scaling behavior with system size and inverse temperature, and compare it to the loop algorithm, whose scaling is known to be one of the best of all QMC methods. Finally we introduce a new and efficient algorithm to measure Green's functions and thus dynamical properties within SSE.Comment: 11 RevTeX pages including 7 figures and 5 table

How to evade a coevolving brood parasite: egg discrimination versus egg variability as host defences

Arms races between avian brood parasites and their hosts often result in parasitic mimicry of host eggs, to evade rejection. Once egg mimicry has evolved, host defences could escalate in two ways: (i) hosts could improve their level of egg discrimination; and (ii) negative frequency-dependent selection could generate increased variation in egg appearance (polymorphism) among individuals. Proficiency in one defence might reduce selection on the other, while a combination of the two should enable successful rejection of parasitic eggs. We compared three highly variable host species of the Afrotropical cuckoo finch Anomalospiza imberbis, using egg rejection experiments and modelling of avian colour and pattern vision. We show that each differed in their level of polymorphism, in the visual cues they used to reject foreign eggs, and in their degree of discrimination. The most polymorphic host had the crudest discrimination, whereas the least polymorphic was most discriminating. The third species, not currently parasitized, was intermediate for both defences. A model simulating parasitic laying and host rejection behaviour based on the field experiments showed that the two host strategies result in approximately the same fitness advantage to hosts. Thus, neither strategy is superior, but rather they reflect alternative potential evolutionary trajectories

Preparation of a transparent and flexible self-standing film of layered titania/isostearate nanocomposite

ArticleJournal of Materials Research. 20(5):1308-1315 (2005)journal articl

Possibility of an ultra-precise optical clock using the 61S0→63P0o6 ^1S_0 \to 6 ^3P^o_0 transition in 171,173^{171, 173}Yb atoms held in an optical lattice

We report calculations designed to assess the ultimate precision of an atomic clock based on the 578 nm $6 ^1S_0 --> 6 ^3P^o_0$ transition in Yb atoms confined in an optical lattice trap. We find that this transition has a natural linewidth less than 10 mHz in the odd Yb isotopes, caused by hyperfine coupling. The shift in this transition due to the trapping light acting through the lowest order AC polarizability is found to become zero at the magic trap wavelength of about 752 nm. The effects of Rayleigh scattering, higher-order polarizabilities, vector polarizability, and hyperfine induced electronic magnetic moments can all be held below a mHz (about a part in 10^{18}), except in the case of the hyperpolarizability larger shifts due to nearly resonant terms cannot be ruled out without an accurate measurement of the magic wavelength.Comment: 4 pages, 1 figur