CO(2)electroreduction on bimetallic Pd-In nanoparticles

CO(2)electroreduction powered by renewable energy is an attractive strategy to recycle air-based carbon. One of the current challenges for the scale up of the technology is that the catalysts that show high faradaic yield at high current density (post-transitional metals such as In, Sn, Bi, Pb) suffer from very high overpotentials of more than 1 V. On the other hand, Pd can convert CO(2)to formate with almost no overpotential, but is readily poisoned by CO and deactivates when trying to reach industrially relevant currents. In this work we show the effect of the interaction of In and Pd in bimetallic nanoparticles, reaching the conclusion that this interaction causes a loss of selectivity towards formate and at the same time suppresses CO poisoning of Pd sites. The results of the catalyst characterization suggest the formation of intermetallic PdIn compounds that in turn cause the aforementioned behavior. Based on these results, it seems that geometric and electronic effects in Pd based intermetallic compounds can alleviate CO poisoning on Pd sites. In the case of PdIn intermetallics this leads to the loss of CO(2)reduction activity, but this strategy may be useful for other electrochemical reactions that suffer from the same problem of deactivation. It remains to be seen if intermetallic compounds of Pd with other elements can yield viable CO(2)reduction catalysts.Catalysis and Surface Chemistr

Electrochemical CO2 reduction on gas diffusion electrodes: enhanced selectivity of In–Bi bimetallic particles and catalyst layer optimization through a design of experiment approach

CO2 electroreduction to formate powered by renewable energy is an attractive strategy to recycle carbon.Electrode materials showing high selectivity for formate at high current densities are post-transition metals such as Sn, In, Pb, Hg, and Bi. Scaling up the CO2 electroreduction technology to industrial size will require, among other things, maximization of selectivity at high current densities. We show here that InBielectrocatalysts provide enhanced selectivity compared to pure In and Bi and that a proper formulation of the catalyst layer can have a profound impact on the performance of gas diffusion electrode electrolyzers. The best performing electrodes screened in this study show nearly 100% current efficiency at current densities up to 400 mA cm−2 for 2 h. Additionally, one electrode was shown to operate at a current density of 200 mA cm−2 for 48 h at a current efficiency of 85% and remained operating with a current efficiency above 50% for 124 h.Catalysis and Surface Chemistr

Condensation and interaction range in harmonic boson traps: a variational approach

For a gas of N bosons interacting through a two-body Morse potential a variational bound of the free energy of a confined system is obtained. The calculation method is based on the Feynman-Kac functional projected on the symmetric representation. Within the harmonic approximation a variational estimate of the effect of the interaction range on the existence of many-particle bound states, and on the N-T phase diagram is obtained.Comment: 14 pages+4 figures, submitted to phys.rev.

Infrared Properties of QCD from Dyson-Schwinger equations

I review recent results on the infrared properties of QCD from Dyson-Schwinger equations. The topics include infrared exponents of one-particle irreducible Green's functions, the fixed point behaviour of the running coupling at zero momentum, the pattern of dynamical quark mass generation and properties of light mesons.Comment: 47 pages, 19 figures, Topical Review to be published in J.Phys.G, v2: typos corrected and some references adde

On the Nature of the Phase Transition in SU(N), Sp(2) and E(7) Yang-Mills theory

We study the nature of the confinement phase transition in d=3+1 dimensions in various non-abelian gauge theories with the approach put forward in [1]. We compute an order-parameter potential associated with the Polyakov loop from the knowledge of full 2-point correlation functions. For SU(N) with N=3,...,12 and Sp(2) we find a first-order phase transition in agreement with general expectations. Moreover our study suggests that the phase transition in E(7) Yang-Mills theory also is of first order. We find that it is weaker than for SU(N). We show that this can be understood in terms of the eigenvalue distribution of the order parameter potential close to the phase transition.Comment: 15 page

Configural and featural processing in humans with congenital prosopagnosia.

Prosopagnosia describes the failure to recognize faces, a deficiency that can be devastating in social interactions. Cases of acquired prosopagnosia have often been described over the last century. In recent years, more and more cases of congenital prosopagnosia (CP) have been reported. In the present study we tried to determine possible cognitive characteristics of this impairment. We used scrambled and blurred images of faces, houses, and sugar bowls to separate featural processing strategies from configural processing strategies. This served to investigate whether congenital prosopagnosia results from process-specific deficiencies, or whether it is a face-specific impairment. Using a delayed matching paradigm, 6 individuals with CP and 6 matched healthy controls indicated whether an intact test stimulus was the same identity as a previously presented scrambled or blurred cue stimulus. Analyses of d´ values indicated that congenital prosopagnosia is a face-specific deficit, but that this shortcoming is particularly pronounced for processing configural facial information

Retinal Degeneration Progression Changes Lentiviral Vector Cell Targeting in the Retina

In normal mice, the lentiviral vector (LV) is very efficient to target the RPE cells, but transduces retinal neurons well only during development. In the present study, the tropism of LV has been investigated in the degenerating retina of mice, knowing that the retina structure changes during degeneration. We postulated that the viral transduction would be increased by the alteration of the outer limiting membrane (OLM). Two different LV pseudotypes were tested using the VSVG and the Mokola envelopes, as well as two animal models of retinal degeneration: light-damaged Balb-C and Rhodopsin knockout (Rho-/-) mice. After light damage, the OLM is altered and no significant increase of the number of transduced photoreceptors can be obtained with a LV-VSVG-Rhop-GFP vector. In the Rho-/- mice, an alteration of the OLM was also observed, but the possibility of transducing photoreceptors was decreased, probably by ongoing gliosis. The use of a ubiquitous promoter allows better photoreceptor transduction, suggesting that photoreceptor-specific promoter activity changes during late stages of photoreceptor degeneration. However, the number of targeted photoreceptors remains low. In contrast, LV pseudotyped with the Mokola envelope allows a wide dispersion of the vector into the retina (corresponding to the injection bleb) with preferential targeting of Müller cells, a situation which does not occur in the wild-type retina. Mokola-pseudotyped lentiviral vectors may serve to engineer these glial cells to deliver secreted therapeutic factors to a diseased area of the retina