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

Nonlocal Effect of Local Nonmagnetic Impurity in High-Tc Superconductors: Induced Local Moment and Huge Residual Resistivity

We study a Hubbard model with a strong onsite impurity potential based on an improved fluctuation-exchange (FLEX) approximation, which we call the GVI-FLEX method. We find that (i) both local and staggered susceptibilities are strongly enhanced around the impurity. By this reason, (ii) the quasiparticle lifetime as well as the local density of states (DOS) are strongly suppressed in a wide area around the impurity (like a Swiss cheese hole), which causes the ``huge residual resistivity'' beyond the s-wave unitary scattering value. These results by the GVI method naturally explains the various impurity effects in HTSC's in a unified way, which had been a long-standing theoretical problem.Comment: 3 pages, submitted to ICM2006, Kyot

〈Research Notes〉Corruption in a repeated psychological game with imperfect monitoring

The aim of this note is to examine the effect of imperfect monitoring on bribery and corrupt practices in public administration. Our findings suggest that if we would reconstruct public service system to exterminate its bribery and corrupt practices, the rate of turnover of the bureaucrat and the amount of the noise in monitoring its behavior should be in the suitable regions respectively. We introduce imperfectness of monitoring the behaviour of the bureaucrat into the infinitely repeated game model developed by Balafoutas (2011). Supposing that the players adopt strategies with two-phases, the corruption and punishment phase, we derive the extent of the amount of the bribe for the bureaucrat and the lobby to sustain collusion in the corruption phase. Moreover, we show a sufficient condition for the two-phase strategies to constitute a psychological Nash equilibrium

Zn-induced wipeout effect on Cu NQR spectra in La2−x_{2-x}Srx_xCu1−y_{1-y}Zny_yO4_4

We report a systematic study of Zn-substitution effect on Cu NQR spectrum for high $T_c$ superconductors La$_{2-x}$Sr$_x$Cu$_{1-y}$Zn$_y$O$_4$ from carrier-underdoped to -overdoped regimes (polycrystalline samples, $x$ =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

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

Composite tetraheteroarylenes and related higher cyclic oligomers of heteroarenes produced by palladium-catalyzed direct coupling

Substantial research interests have been focused on cyclic π-conjugated molecules owing to their unique chemical and physical properties. By constructing hybrid aromatic arrays within these cyclic systems, new series of composite macrocycles would be provided. Our group has been studying the construction of such hybrids by adopting the palladiumcatalyzed direct coupling of heteroaromatics. We herein report the synthesis and characterization of thiophene-thiazole composite macrocycles. X-ray diffraction analyses revealed that some of these coupling products exhibit characteristic helical assemblies in the solid state. Additionally, we synthesized a heteroarene-fused cyclooctatetraene composed of four different heteroaryl fragments