2,928 research outputs found
Coordination and Evolutionary Network Formation with Asymmetric Link Costs: Part One
We analyze a dynamic implication of an evolutionary process in a population where both actions and network structures changes over time. At every period, a coordination game is played by players who are linked with each other. An asymmetric cost of a link is incorporated. Under this setting each player myopically adopts with its circumstance consisting of the network structure and the action profile. In a stochastically stable state there are link cost patterns such that all players play a pareto dominant equilibrium strategy of coordination game. This is the most different result from a standard stochastic evolutionary models that selects a risk dominant equilibrium.Network formation, Coordination game, Stochastic evolution, Asymmetric link cost, Pareto dominant equilibrium, Risk dominant equilibrium
Zn-induced wipeout effect on Cu NQR spectra in LaSrCuZnO
We report a systematic study of Zn-substitution effect on Cu NQR spectrum for
high superconductors LaSrCuZnO from
carrier-underdoped to -overdoped regimes (polycrystalline samples, =0.10,
0.15, and 0.20). We observed no appreciable wipeout effect for the overdoped
samples, a gradual and partial wipeout effect below about 80 K for the
optimally doped ones, and very abrupt and full wipeout effect below about 40 K
for the underdoped ones. The wipeout effect indicates a highly enhanced
spectral weight of Cu spin fluctuations at a low frequency. We associate the
wipeout effect with a Zn-induced local magnetism far above 40 K and with a
localization effect below 40 K.Comment: 2 pages, 3 figures, accepted for publication in Physica C (LT23,
Hiroshima 2002
High Catalytic Activity of Heteropolynuclear Cyanide Complexes Containing Cobalt and Platinum Ions: Visible-Light Driven Water Oxidation
A near-stoichiometric amount of O_2 was evolved as observed in the visible-light irradiation of an aqueous buffer (pH 8) containing [Ru^(II)(2,2′-bipyridine)_3] as a photosensitizer, Na_2S_2O_8 as a sacrificial electron acceptor, and a heteropolynuclear cyanide complex as a water-oxidation catalyst. The heteropolynuclear cyanide complexes exhibited higher catalytic activity than a polynuclear cyanide complex containing only Co^(III) or Pt^(IV) ions as C-bound metal ions. The origin of the synergistic effect between Co and Pt ions is discussed in relation to electronic and local atomic structures of the complexes
Subtle Changes, Dramatic Effects: Homogeneous Catalysis of the Oxygen-Reduction Reaction
Photocatalytic degradation of phenolic pollutants using N-methylquinolinium and 9-mesityl-10-methylacridinium salts
[EN] The photodegradation of a mixture of phenolic pollutants including: phenol (P), orto-phenylphenol (OPP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) was accomplished using two organic cationic photocatalysts, namely N-methylquinolinium (NMQ(+)) and 9-mesityl-10-methylacridinium (Mes-Acr-Me+) salts, due to their singular photophysical and redox properties. On one hand, NMQ+ exhibits more energetic excited states and accordingly more favorable redox potentials than Mes-Acr-Me+; on the other hand, NMQ(+) absorption reaches only up to 380 nm, while Mes-Acr-Me+ extends in the visible up to 480 nm. Evaluation of the efficiency of both photocatalysts, revealed that the highest level of photodegradation was achieved when they were employed at 20% mol. Specifically, with NMQ(+), removal of the pollutants was completed within 24 h of irradiation. Even more, irradiation time could be shortened from 24 to 8 h, since high levels of removal were already achieved (93%, 100%, 100% and 82% for P, OPP, TCP and PCP, respectively). Albeit, Mes-Acr-Me+ was not as effective, and best results were obtained using 20% mol upon 24 h of irradiation. Under these conditions, removal of PCP was 80%, while TCP was 40%, OPP 30% and P resulted in the most recalcitrant contaminant with only 10% of removal. Next, NMQ(+) and Mes-Acr-Me+ were separately supported onto Zeolite Y, an inert inorganic support (Y-NMQ(+) and Y-Mes-Acr-Me+), and elemental analyses revealed a loading of ca. 13% and 15% weight for NMQ(+) and Mes-Acr-Me+, respectively. Upon heterogenization, in the case of Y-NMQ(+), the extent of removal was lower than the one achieved in the homogeneous photodegradations. On the contrary, performance of Y-Mes-Acr-Me+ improved, because of its enhanced photostability; thus, upon 46 h irradiation, 98%, 80%, 40% and 26% for PCP, TCP, OPP and P, respectively, was achieved. Moreover, their efficiency was maintained upon second use. Steady-state and time-resolved fluorescence quenching revealed that every pollutant was able to quench the singlet excited state of both 1(NMQ(+))* and 1(Mes-Acr-Me+)*, with kinetic rate constants in the order of the diffusion limit. Thus, Type I photooxidation happening through the singlet excited state of either photocatalyst was the main operating process in the photodegradation of the studied pollutants.Financial support from Spanish Government (Grant SEV-20160683) is gratefully acknowledged. Financial support from VLC/Campus. R. Martinez-Haya thanks financial support for a predoctoral contract from Apadrina la Ciencia Association and Ford Espana/Ford Motor Company Fund.Martínez-Haya, R.; Luna, MM.; Hijarro, A.; Martinez-Valero, E.; Miranda Alonso, MÁ.; Marín García, ML. (2019). Photocatalytic degradation of phenolic pollutants using N-methylquinolinium
and 9-mesityl-10-methylacridinium salts. Catalysis Today. 328:243-251. https://doi.org/10.1016/j.cattod.2019.01.045S24325132
Thermal efficiency of a thermocell made of Prussian blue analogues
Recently, it was reported that a thermocell can convert temperature into electric energy by using the difference in the thermal coefficient (α = dV/dT) of the redox potential (V) between the cathode and anode materials. Among battery materials, Prussian blue analogues (PBAs) are promising materials for thermocell, because α changes from approximately −0.3 mV/K in NaxMn[Fe(CN)6]0.83 3.5 H2O (NMF83) to approximately 1.3 mV/K in NaxCo[Fe(CN)6]0.92,9H2O (NCF90). In this work, we systematically investigated the thermal efficiency (η) of the NMF83/NCF90 thermocell relative to the difference (ΔT) between low (TL = 282 K) and high (TH = 292–338 K) temperatures. We found that the thermal efficiency (η) increased proportionally with ΔT. The linear increase in η is ascribed to the linear increase in the cell voltage (Vcell) and the charge (QNCF90) extracted from NCF90. Moreover, η reached 3.19% at ΔT = 56 K, which corresponds to 19% of the Carnot efficiency (ηcarnot = 17.0%). We further confirmed that the magnitude of QNCF90 is quantitatively reproduced by the slopes of the discharge curves of NMF83 and NCF90
Configuration entropy effect on temperature coefficient of redox potential of P2-Na x CoO2
The temperature coefficient (α) of redox potential (V) is a significant material parameter that coverts thermal energy into electric energy. In this paper, we determined α of P2-type Na x CoO2 against the Na+ concentration (x). The solid component (α solid) of α scatters from −0.18 to 0.64 mV K−1. The phase separation model cannot reproduce the x-dependence even qualitatively. We interpreted the unexpected disagreement in terms of the residual configuration entropy in the pseudo-disordered region between the Na+ ordered phases
Cooper pair delocalization in disordered media
We discuss the effect of disorder on the coherent propagation of the bound
state of two attracting particles. It is shown that a result analogous to the
Anderson theorem for dirty superconductors is also valid for the Cooper
problem, namely, that the pair wave function is extended beyond the
single-particle localization length if the latter is large. A physical
justification is given in terms of the Thouless block-scaling picture of
localization. These arguments are supplemented by numerical simulations. With
increasing disorder we find a transition from a regime in which the interaction
delocalizes the pair to a regime in which the interaction enhances
localization.Comment: 5 pages, RevTex with 2 figures include
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