Enhancement of service life of polymer electrolyte fuel cells through application of nanodispersed ionomer

Copyright © 2020 The Authors, some rights reserved.In polymer electrolyte fuel cells (PEFCs), protons from the anode are transferred to the cathode through the ionomer membrane. By impregnating the ionomer into the electrodes, proton pathways are extended and high proton transfer efficiency can be achieved. Because the impregnated ionomer mechanically binds the catalysts within the electrode, the ionomer is also called a binder. To yield good electrochemical performance, the binder should be homogeneously dispersed in the electrode and maintain stable interfaces with other catalyst components and the membrane. However, conventional binder materials do not have good dispersion properties. In this study, a facile approach based on using a supercritical fluid is introduced to prepare a homogeneous nanoscale dispersion of the binder material in aqueous alcohol. The prepared binder exhibited high dispersion characteristics, crystallinity, and proton conductivity. High performance and durability were confirmed when the binder material was applied to a PEFC cathode electrode11sciescopu

Fluid Models of Many-server Queues with Abandonment

We study many-server queues with abandonment in which customers have general service and patience time distributions. The dynamics of the system are modeled using measure- valued processes, to keep track of the residual service and patience times of each customer. Deterministic fluid models are established to provide first-order approximation for this model. The fluid model solution, which is proved to uniquely exists, serves as the fluid limit of the many-server queue, as the number of servers becomes large. Based on the fluid model solution, first-order approximations for various performance quantities are proposed

Persistence properties of a system of coagulating and annihilating random walkers

We study a d-dimensional system of diffusing particles that on contact either annihilate with probability 1/(q-1) or coagulate with probability (q-2)/(q-1). In 1-dimension, the system models the zero temperature Glauber dynamics of domain walls in the q-state Potts model. We calculate P(m,t), the probability that a randomly chosen lattice site contains a particle whose ancestors have undergone exactly (m-1) coagulations. Using perturbative renormalization group analysis for d < 2, we show that, if the number of coagulations m is much less than the typical number M(t), then P(m,t) ~ m^(z/d) t^(-theta), with theta=d Q + Q(Q-1/2) epsilon + O(epsilon^2), z=(2Q-1) epsilon + (2 Q-1) (Q-1)(1/2+A Q) epsilon^2 +O(epsilon^3), where Q=(q-1)/q, epsilon =2-d and A =-0.006. M(t) is shown to scale as t^(d/2-delta), where delta = d (1 -Q)+(Q-1)(Q-1/2) epsilon+ O(epsilon^2). In two dimensions, we show that P(m,t) ~ ln(t)^(Q(3-2Q)) ln(m)^((2Q-1)^2) t^(-2Q) for m << t^(2 Q-1). The 1-dimensional results corresponding to epsilon=1 are compared with results from Monte Carlo simulations.Comment: 12 pages, revtex, 5 figure

Glueballs of Super Yang-Mills from Wrapped Branes

In this paper we study qualitative features of glueballs in N=1 SYM for models of wrapped branes in IIA and IIB backgrounds. The scalar mode, 0++ is found to be a mixture of the dilaton and the internal part of the metric. We carry out the numerical study of the IIB background. The potential found exhibits a mass gap and produces a discrete spectrum without any cut-off. We propose a regularization procedure needed to make these states normalizable.Comment: 22 pages plus a appendixes, 2 figure

Correlation Functions for Diffusion-Limited Annihilation, A + A -> 0

The full hierarchy of multiple-point correlation functions for diffusion-limited annihilation, A + A -> 0, is obtained analytically and explicitly, following the method of intervals. In the long time asymptotic limit, the correlation functions of annihilation are identical to those of coalescence, A + A -> A, despite differences between the two models in other statistical measures, such as the interparticle distribution function

Measurement of the Branching Fraction for B->eta' K and Search for B->eta'pi+

We report measurements for two-body charmless B decays with an eta' meson in the final state. Using 11.1X10^6 BBbar pairs collected with the Belle detector, we find BF(B^+ ->eta'K^+)=(79^+12_-11 +-9)x10^-6 and BF(B^0 -> eta'K^0)=(55^+19_-16 +-8)x10^-6, where the first and second errors are statistical and systematic, respectively. No signal is observed in the mode B^+ -> eta' pi^+, and we set a 90% confidence level upper limit of BF(B^+-> eta'pi^+) eta'K^+- decays is investigated and a limit at 90% confidence level of -0.20<Acp<0.32 is obtained.Comment: Submitted to Physics Letters

Observation of Cabibbo-suppressed and W-exchange Lambda_c^+ baryon decays

We present measurements of the Cabibbo-suppressed decays Lambda_c^+ --> Lambda0 K+ and Lambda_c^+ --> Sigma0 K+ (both first observations), Lambda_c^+ --> Sigma+ K+ pi- (seen with large statistics for the first time), Lambda_c^+ --> p K+ K- and Lambda_c^+ --> p phi (measured with improved accuracy). Improved branching ratio measurements for the decays Lambda_c^+ --> Sigma+ K+ K- and Lambda_c^+ --> Sigma+ phi, which are attributed to W-exchange diagrams, are shown. We also present the first evidence for Lambda_c^+ --> Xi(1690)^0 K+ and set an upper limit on the non-resonant decay Lambda_c^+ --> Sigma+ K+ K-. This analysis was performed using 32.6 fb^{-1} of data collected by the Belle detector at the asymmetric e+ e- collider KEKB.Comment: Submitted to Phys. Lett. B. v2: A small correction to the Authorlist was made. An earlier version of this analysis was released as BELLE-CONF-0130, hep-ex/010800

Measurements of Branching Fractions and Decay Amplitudes in B-> J/\psi K^* decays

The branching fractions and the decay amplitudes of B -> J/psi K^* decays are measured in a 29.4/fb data sample collected with the Belle detector at the KEKB electron-positron collider. The decay amplitudes of helicity states of the J/psi K^* system are determined from the full angular distribution of the final state particles in the transversity basis. The branching fractions are measured to be (1.29\pm0.05\pm0.13) \times 10^{-3} for neutral mesons and (1.28\pm0.07\pm0.14) \times 10^{-3} for charged mesons. The measured longitudinal and transverse (perpendicular to the transversity plane) amplitudes are |A_0|^2 = 0.62\pm0.02\pm0.03 and |A_{\perp}|^2 = 0.19\pm0.02\pm0.03, respectively. The value of |A_{\perp}|^2 shows that the CP even component dominates in the B^0 \to J/\psi K^{*0}(K_S\pi^0) decay.Comment: 17 pages, 3 figures, 5 tables, to appear in Phys. Lett.

Measurement of the inclusive semileptonic branching fraction of B mesons and |Vcb|

We present a measurement of the electron spectrum from inclusive semileptonic {\it B} decay, using 5.1 fb$^{-1}$ of $\Upsilon(4S)$ data collected with the Belle detector. A high-momentum lepton tag was used to separate the semileptonic {\it B} decay electrons from secondary decay electrons. We obtained the branching fraction, ${\cal B}(B\to X e^+ \nu) = (10.90 \pm 0.12 \pm 0.49)$, with minimal model dependence. From this measurement, we derive a value for the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}| = 0.0408 \pm 0.0010 {\rm (exp)} \pm 0.0025{\rm (th)}$.Comment: 16 pages, 3 figures, 3 table