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This article focuses on the Electrochemical Society meeting held in Los Angeles, California. The first symposium of the Physical and Analytical Electrochemistry Division focused on Durability and Reliability of Low-Temperature Fuel Cells and Fuel Cell Systems. This symposium presented Outstanding Student Paper Awards to students of various universities of the United States. For example, Vishal Mittal of the University of Connecticut got the award for his paper entitled, "Factors Accelerating Membrane Degradation Rate and the Underlying Degradation Mechanism in PEMFC." In this paper, experiments were performed to elucidate the factors and conditions important for photoelectromagnetic degradation.

Particle flows in spatial networks are susceptible to congestion. In this paper, we analyze the phase transitions of these networks to a state of congested transport and the influence of both topology and spatial dynamics on its emergence. We systematically show that the value of the critical loading rate at which congestion emerges is affected by the addition of spatial dynamics, changing the nature of this transition from a continuous to a discontinuous one. Our numerical results are confirmed by introducing an analytical solvable framework. As a case of study, we explore the implications of our findings in the San Francisco road network where we can locate the roads that originate the congested phase. These roads are spatially constrained, and not necessarily those with high betweenness as predicted by models without spatial dynamics. [ABSTRACT FROM AUTHOR]

“TRAO FUNS” is a project to survey the Gould Belt’s clouds in molecular lines. This paper presents its first results on the central region of the California molecular cloud, L1478. We performed on-the-fly mapping observations using the Taeduk Radio Astronomy Observatory 14 m single-dish telescope equipped with a 16 multibeam array covering a ∼1.0 square degree area of this region using , mainly tracing low-density clouds, and a ∼460 square arcminute area using , mainly tracing dense cores. and were also used simultaneously to map a ∼440 square arcminute area of this region. We identified 10 filaments by applying the dendrogram technique to the data cube and 8 dense cores using FellWalker. Basic physical properties of filaments such as mass, length, width, velocity field, and velocity dispersion are derived. It is found that L1478 consists of several filaments with slightly different velocities. Particularly, the filaments that are supercritical are found to contain dense cores detected in . A comparison of nonthermal velocity dispersions derived from and for the filaments and dense cores indicates that some of the dense cores share kinematics similar to those of the surrounding filaments, while several dense cores have different kinematics from those of their filaments. This suggests that the formation mechanism of dense cores and filaments can be different in individual filaments depending on their morphologies and environments. [ABSTRACT FROM AUTHOR]

In a recent experiment at Lawrence Berkeley National Laboratory (Geddes et al 2008 Phys. Rev. Lett. 100 215004), electron bunches with about 1MeV mean energy and small absolute energy spread (about 0.3 MeV) were produced by plasma wave breaking on a downward density ramp. It was then speculated that such a bunch might be accelerated further in a plasma of low constant density, while mostly preserving its small absolute energy spread. This would then lead to a bunch with a high mean energy and very low relative energy spread. In this paper, trapping of a low-energy, low-spread electron bunch on a downward density ramp, followed by acceleration in a constant-density plasma, has been explored through particle-in-cell simulations. It has been found that the scheme works best when it is used as a separate injection stage for a laser-wakefield accelerator, where the injection and acceleration stages are separated by a vacuum gap. [ABSTRACT FROM AUTHOR]

We study the relationship between molecular gas and dust in the California Molecular Cloud over an unprecedented dynamic range of cloud depth (AV = 3–60 mag). We compare deep Herschel-based measurements of dust extinction with observations of the 12CO, 13CO, and C18O J = 2 − 1 lines on sub-parsec scales across the cloud. We directly measure the ratio of CO integrated intensity to dust extinction to derive the CO X-factor at over 105 independent locations in the cloud. Confirming an earlier study, we find that no single 12CO X-factor can characterize the molecular gas in the cold (Tdust ≤ 20) regions of the cloud that account for most of its mass. We are able to derive a single-valued X-factor for all three CO isotopologues in the warm (Tdust > 25 K) material that is spatially coincident with an H ii region surrounding the star LkHα 101. We derive the LTE CO column densities for 13CO and C18O since we find both lines are relatively optically thin. In the warm cloud material, CO is completely in the gas phase and we are able to recover the total 13CO and C18O abundances. Using CO abundances and deep Herschel observations, we measure lower bounds to the freeze-out of CO onto dust across the whole cloud, finding some regions having CO depleted by a factor of >20. We construct the first maps of depletion that span the extent of a giant molecular cloud. Using these maps we identify 75 depletion-defined cores and discuss their physical nature. [ABSTRACT FROM AUTHOR]

We analyze the gas mass distribution, the gas kinematics, and the young stellar objects of the California Molecular Cloud L1482 filament. The mean Gaia DR2 YSO distance is pc. In terms of the gas, the line-mass (M/L) profiles are symmetric scale-free power laws consistent with cylindrical geometry. We calculate the gravitational potential and field profiles based on these. Our IRAM 30 m multi-tracer position–velocity diagrams highlight twisting and turning structures. We measure the C18O velocity profile perpendicular to the southern filament ridgeline. The profile is regular, confined (projected r ≲ 0.4 pc), antisymmetric, and, to first order, linear, with a break at r ∼ 0.25 pc. We use a simple solid-body rotation toy model to interpret it. We show that the centripetal force, compared to gravity, increases toward the break; when the ratio of forces approaches unity, the profile turns over, just before the implied filament breakup. The timescales of the inner (outer) gradients are ∼0.7 (6.0) Myr. The timescales and relative roles of gravity to rotation indicate that the structure is stable, long lived (∼a few times 6 Myr), and undergoing outside-in evolution. This filament has practically no star formation, a perpendicular Planck plane-of-the-sky magnetic field morphology, and 2D "zig-zag" morphology, which together with the rotation profile lead to the suggestion that the 3D shape is a "corkscrew" filament. These results, together with results in other regions, suggest evolution toward higher densities as rotating filaments shed angular momentum. Thus, magnetic fields may be an essential feature of high-mass (M ∼ 105M⊙) cloud filament evolution toward cluster formation. [ABSTRACT FROM AUTHOR]

We report the first high spatial resolution measurement of magnetic fields surrounding LkHα 101, part of the Auriga–California molecular cloud. The observations were taken with the POL-2 polarimeter on the James Clerk Maxwell Telescope within the framework of the B-fields In Star-forming Region Observations (BISTRO) survey. Observed polarization of thermal dust emission at 850 μm is found to be mostly associated with the redshifted gas component of the cloud. The magnetic field displays a relatively complex morphology. Two variants of the Davis–Chandrasekhar–Fermi method, unsharp masking and structure function, are used to calculate the strength of magnetic fields in the plane of the sky, yielding a similar result of BPOS ∼ 115 μG. The mass-to-magnetic-flux ratio in critical value units, λ ∼ 0.3, is the smallest among the values obtained for other regions surveyed by POL-2. This implies that the LkHα 101 region is subcritical, and the magnetic field is strong enough to prevent gravitational collapse. The inferred δB/B0 ∼ 0.3 implies that the large-scale component of the magnetic field dominates the turbulent one. The variation of the polarization fraction with total emission intensity can be fitted by a power law with an index of α = 0.82 ± 0.03, which lies in the range previously reported for molecular clouds. We find that the polarization fraction decreases rapidly with proximity to the only early B star (LkHα 101) in the region. Magnetic field tangling and the joint effect of grain alignment and rotational disruption by radiative torques can potentially explain such a decreasing trend. [ABSTRACT FROM AUTHOR]

Presents some of the highlights of the 193rd Meeting of the Electrochemical Society Incorporated (ECS) held for the first time in San Diego, California in May. Number of attendees; Number of papers presented in 35 symposia; Number of booths and displays presented; Statements from C. Judson King, provost and senior vice-president of the University of California (UC); Information on Dr. Walther G. Grot's award address. INSET: Board highlights.

We report Arecibo 21 cm absorption-emission observations to characterize the physical properties of neutral hydrogen (H i) in the proximity of five giant molecular clouds (GMCs): Taurus, California, Rosette, Mon OB1, and NGC 2264. Strong H i absorption was detected toward all 79 background-continuum sources in the ∼60 × 20 square degree region. Gaussian decompositions were performed to estimate temperatures, optical depths, and column densities of the cold and warm neutral medium (CNM and WNM). The properties of individual CNM components are similar to those previously observed along random Galactic sightlines and in the vicinity of molecular clouds, suggesting a universality of cold H i properties. The CNM spin temperature (Ts) histogram peaks at ∼50 K. The turbulent Mach numbers of CNM components vary widely, with a typical value of ∼4, indicating that their motions are supersonic. About 60% of the total H i gas is WNM, and nearly 40% of the WNM lies in thermally unstable regime 500–5000 K. The observed CNM fraction is higher around GMCs than in diffuse regions, and increases with increasing column density () to a maximum of ∼75%. On average, the optically thin approximation () underestimates the total column density by ∼21%, but we find large regional differences in the relationship between and the required correction factor, f = . We examine two different methods (linear fit of f versus log10() and uniform Ts) to correct for opacity effects using emission data from the GALFA-H i survey. We prefer the uniform Ts method because the linear relationship does not produce convincing fits for all subregions. [ABSTRACT FROM AUTHOR]