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José de San Martín, Argentina

Kappes M.,Ohio State University | Frankel G.S.,Ohio State University | Sridhar N.,DNV Columbus Inc. | Carranza R.M.,CNEA
Journal of the Electrochemical Society | Year: 2012

Corrosion tests with gaseous H 2S require special facilities with safety features, because H 2S is a toxic and flammable gas. The possibility of replacing H 2S with thiosulfate (S 2O 3 2-), a non-toxic anion, for studying stress corrosion cracking of stainless and carbon steels in H 2S solutions was first proposed by Tsujikawa in 1993. H 2S production was detected in presence of carbon steel corroding in acidified thiosulfate-containing solutions. In this paper, the kinetics of H 2S evolution are used to estimate the range of partial pressure of H 2S that can be simulated with thiosulfate solutions. It was determined that acid brines containing 10 -4 M and 10 -3 M S 2O 3 2- could be used for replacing continuous bubbling of dilute H 2SN 2 mixtures in tests of degradation of carbon steels, with H 2S partial pressures ranging between 0.03 and 0.56 kPa. The kinetics of H 2S production were compared with the amount of sulfur in side reactions, like formation of iron sulfide films and elemental sulfur. © 2012 The Electrochemical Society. Source

Carlo G.G.,CNEA
Physical Review Letters | Year: 2012

It has been recently found that the so-called isoperiodic stable structures (ISSs) have a fundamental role in the classical current behavior of dissipative ratchets. Here I analyze their quantum counterparts, the quantum ISSs (QISSs), which have a fundamental role in the quantum current behavior. QISSs have the simple attractor shape of those ISSs which settle down in short times. However, in the majority of the cases they are strongly different from the ISSs, looking approximately the same as the quantum chaotic attractors that are at their vicinity in parameter space. By adding thermal fluctuations of the size of eff to the ISSs I am able to obtain very good approximations to the QISSs. I conjecture that in general, quantum chaotic attractors could be well approximated by means of just the classical information of a neighboring ISS plus thermal fluctuations. I expect to find this behavior in quantum dissipative systems in general. © 2012 American Physical Society. Source

Carlo G.G.,CNEA | Ermann L.,CNRS Laboratory for Theoretical Physics | Borondo F.,Autonomous University of Madrid | Benito R.M.,Technical University of Madrid
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

The transitory and stationary behavior of a quantum chaotic ratchet consisting of a biharmonic potential under the effect of different drivings in contact with a thermal environment is studied. For weak forcing and finite, we identify a strong dependence of the current on the structure of the chaotic region. Moreover, we have determined the robustness of the current against thermal fluctuations in the very weak coupling regime. In the case of strong forcing, the current is determined by the shape of a chaotic attractor. In both cases the temperature quickly stabilizes the ratchet, but in the latter it also destroys the asymmetry responsible for the current generation. Finally, applications to isomerization reactions are discussed. © 2011 American Physical Society. Source

Vitturi A.,National Institute of Nuclear Physics, Italy | Sofia H.M.,CNEA
Progress of Theoretical Physics Supplement | Year: 2012

Two-particle transfer processes induced by light and heavy ions are known to be an ideal dynamical tool for extracting information on nuclear pairing correlations. The procedure is however not unique and different reaction mechanism models (ranging from microscopic correlated successive one-particle transfer to collective macroscopic models) can be introduced to establish a link with the structural aspects of initial and final states. We briefly review the subject with special attention to the novel features arising in systems close to the drip lines from the weak binding situation and the consequent role of continuum states. Source

Raviola L.A.,CNEA | Carlo G.G.,CNEA | Rivas A.M.F.,CNEA | Rivas A.M.F.,National University of General Sarmiento
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

We study the stability of classical structures in chaotic systems when a dissipative quantum evolution takes place. We consider a paradigmatic model, the quantum baker map in contact with a heat bath at finite temperature. We analyze the behavior of the purity, fidelity and Husimi distributions corresponding to initial states localized on short periodic orbits (scar functions) and map eigenstates. Scar functions, that have a fundamental role in the semiclassical description of chaotic systems, emerge as robust relative to other states (which are localized on classical structures) against environmental perturbations. Also, purity and fidelity show a complementary behavior as decoherence measures. © 2010 The American Physical Society. Source

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