Battery workshop

The workshop was attended by representatives from industry and government. The requirements for energy storage and the plans for battery development were reviewed. The workshop followed a debate format, with the objective of recommending improvements to the development plans presented by NASA and the Air Force. The issues addressed were: (1) significant technology deficiencies which can be identified; (2) adequacy of current and proposed programs to resolve the technology deficiencies identified; (3) additional tasks which should be undertaken, including benefits and timing; and (4) lowest priority items in the presently planned program, both in content and in timing

Polarization Diagnostics for Cool Core Cluster Emission Lines

The nature of the interaction between low-excitation gas filaments at ~104 K, seen in optical line emission, and diffuse X-ray emitting coronal gas at ~107 K in the centers of galaxy clusters remains a puzzle. The presence of a strong, empirical correlation between the two gas phases is indicative of a fundamental relationship between them, though as yet of undetermined cause. The cooler filaments, originally thought to have condensed from the hot gas, could also arise from a merger or the disturbance of cool circumnuclear gas by nuclear activity. Here, we have searched for intrinsic line emission polarization in cool core galaxy clusters as a diagnostic of fundamental transport processes. Drawing on developments in solar astrophysics, direct energetic particle impact induced polarization holds the promise to definitively determine the role of collisional processes such as thermal conduction in the ISM physics of galaxy clusters, while providing insight into other highly anisotropic excitation mechanisms such as shocks, intense radiation fields, and suprathermal particles. Under certain physical conditions, theoretical calculations predict of the order of 10% polarization. Our observations of the filaments in four nearby cool core clusters place stringent upper limits ( 0.1%) on the presence of emission line polarization, requiring that if thermal conduction is operative, the thermal gradients are not in the saturated regime. This limit is consistent with theoretical models of the thermal structure of filament interfacesPeer reviewe

Photoluminescence from nanocrystalline graphite monofluoride

We synthesize and study the structural and optical properties of nanocrystalline graphene monofluoride and graphite monofluoride, which are carbon-based wide bandgap materials. Using laser excitations 2.41 - 5.08 eV, we identify six emission modes of graphite monofluoride, spanning the visible spectrum from red to violet. The energy and linewidth of the modes point to defect-induced midgap states as the source of the photoemission. We discuss possible candidates. Our findings open the window to electro-optical applications of graphene fluoride.Comment: 11 pages including supporting information, 2 figure

Concentration of Metals Associated with the Native Copper Deposits of Northern Michigan

The Keweenaw Peninsula of northern Michigan is home to the largest accumulation of native copper in the world. Native copper deposits are hosted in the 1.1 billion-year old midcontinent rift which extends from Kansas, up through Lake Superior, around into lower Michigan, but is only exposed in the Keweenaw region. Native copper is found in the vesicular and brecciated flow tops of the volcanism associated with this rift, within the interflow conglomerate that developed in-between individual flows, and also minor native copper deposits are found with the copper sulfide deposits in the Nonesuch Shale. The purpose of this study was to examine the concentrations of zinc, lead, and silver associated with native copper in each of these depositional environments in hopes of gaining an understanding of the geochemistry of the native copper in this area. Eleven copper samples were examined using X-Ray fluorescence spectroscopy. Three geologic areas of copper deposition studied were: the brecciated and amygdaloidal flow tops of the Portage Lake Volcanics (PLV), conglomerate layers in between PLV basalt flows, and fracture fillings of the Nonesuch Shale, as seen in the White Pine Copper Mine. The volcanic flow tops exhibited decreased Zn, Pb, and Ag with increasing Cu. Within the interflow conglomerates, chemical relationships showed an increase in Zn but a decrease in Pb and Ag with increasing Cu. In both of these sets, chemical ratios of Pb/Zn decreased with increasing Cu/Ag in a decay-like curve. The native copper as fracture filling in shale had a different chemical signature in which the Ag increased with Cu. Chemical data from this study may help in our understanding of fluid composition associated with hydrothermal copper mineralization

Dynamics of explosive degassing of magma: Observations of fragmenting two-phase flows

Liquid explosions, generated by rapid degassing of strongly supersaturated liquids, have been investigated in the laboratory with a view to understanding the basic physical processes operating during bubble nucleation and growth and the subsequent behavior of the expanding two-phase flow. Experiments are carried out in a shock tube and are monitored by high-speed photography and pressure transducers. Theoretical CO_2 supersaturations up to 455 times the ambient saturation concentration are generated by a chemical reaction; K_2CO_3 solution is suddenly injected into an excess of HCl solution in such a way as to mix the two solutions rapidly. Immediately after the injection event, a bubble nucleation delay of a few milliseconds is followed by rapid nucleation and explosive expansion of CO_2 bubbles forming a highly heterogeneous foam. Enhanced diffusion due to advection in the flow coupled with continuous mixing of the reactants, and hence on-going bubble nucleation after injection, generates an increasingly accelerating flow until the reactants become depleted at peak accelerations of around 150 g and velocities of about 15 m s^(−1). Stretching of the accelerating two-phase mixture enhances the mixing. Liberation of CO_2 vapor is spatially inhomogeneous leading to ductile fragmentation occurring throughout the flow in regions of greatest gas release as the consequence of the collision and stretching of fluid streams. The violence of the eruptions is controlled by using different concentrations of the HCl and K_2CO_3 solutions, which alters the CO_2 supersaturation and yield and also the efficiency of the mixing process. Peak acceleration is proportional to theoretical supersaturation. Pressure measurements at the base of the shock tube show an initial nucleation delay and a pressure pulse related to the onset of explosive bubble formation. These chemically induced explosions differ from liquid explosions created in other experiments. In explosions caused by sudden depressurization of CO_2-saturated water, the bubbles nucleate uniformly throughout the liquid in a single nucleation event. Subsequent bubble growth causes the two-phase mixture to be accelerated upward at nearly constant accelerations. Explosively boiling liquids, in which heterogeneous nucleation is suppressed, experience an evaporation wave which propagates down into the liquid column at constant average velocity. Fragmentation occurs at the sharply defined leading edge of the wavefront. The chemical flows effectively simulate highly explosive volcanic eruptions as they are comparable in terms of flow densities, velocities, accelerations, and in the large range of scales present. The large accelerations cause strong extensional strain and longitudinal deformation. Comparable deformation rates in volcanic systems could be sufficient to approach conditions for brittle fragmentation. Tube pumice is a major component of plinian deposits and ignimbrites and preserves evidence of accelerating flow conditions

Dynamics of magnetization coupled to a thermal bath of elastic modes

We study the dynamics of magnetization coupled to a thermal bath of elastic modes using a system plus reservoir approach with realistic magnetoelastic coupling. After integrating out the elastic modes we obtain a self-contained equation for the dynamics of the magnetization. We find explicit expressions for the memory friction kernel and hence, {\em via} the Fluctuation-Dissipation Theorem, for the spectral density of the magnetization thermal fluctuations. For magnetic samples in which the single domain approximation is valid, we derive an equation for the dynamics of the uniform mode. Finally we apply this equation to study the dynamics of the uniform magnetization mode in insulating ferromagnetic thin films. As experimental consequences we find that the fluctuation correlation time is of the order of the ratio between the film thickness, $h$, and the speed of sound in the magnet and that the line-width of the ferromagnetic resonance peak should scale as $B_1^2h$ where $B_1$ is the magnetoelastic coupling constant.Comment: Revised version as appeared in print. 12 pages 9 figure

The long-period Galactic Cepheid RS Puppis - II. 3D structure and mass of the nebula from VLT/FORS polarimetry

The long-period Cepheid RS Pup is surrounded by a large dusty nebula reflecting the light from the central star. Due to the changing luminosity of the central source, light echoes propagate into the nebula. This remarkable phenomenon was the subject of Paper I.The origin and physical properties of the nebula are however uncertain: it may have been created through mass loss from the star itself, or it could be the remnant of a pre-existing interstellar cloud. Our goal is to determine the 3D structure of the nebula, and estimate its mass. Knowing the geometrical shape of the nebula will also allow us to retrieve the distance of RS Pup in an unambiguous manner using a model of its light echoes (in a forthcoming work). The scattering angle of the Cepheid light in the circumstellar nebula can be recovered from its degree of linear polarization. We thus observed the nebula surrounding RS Pup using the polarimetric imaging mode of the VLT/FORS instrument, and obtained a map of the degree and position angle of linear polarization. From our FORS observations, we derive a 3D map of the distribution of the dust, whose overall geometry is an irregular and thin layer. The nebula does not present a well-defined symmetry. Using a simple model, we derive a total dust mass of M(dust) = 2.9 +/- 0.9 Msun for the dust within 1.8 arcmin of the Cepheid. This translates into a total mass of M(gas+dust) = 290 +/- 120 Msun, assuming a dust-to-gas ratio of 1.0 +/- 0.3 %. The high mass of the dusty nebula excludes that it was created by mass-loss from the star. However, the thinness nebula is an indication that the Cepheid participated to its shaping, e.g. through its radiation pressure or stellar wind. RS Pup therefore appears as a regular long-period Cepheid located in an exceptionally dense interstellar environment.Comment: 14 pages, 21 figures. Accepted for publication in A&

Comparison of Inedible Egg Product and Spray-Dried Plasma as Sources of Protein for Weanling Pigs

Pigs were weaned at approximately 18 days of age and fed diets containing inedible egg product, spray-dried plasma (SDP), or the combination of both for 2 weeks postweaning. They then received a common diet for an additional 2 weeks after the treatment period. The impact of these dietary ingredients on growth performance was evaluated. Inedible egg product did not improve growth or feed efficiency of pigs compared with those fed the control diet during the 2-week treatment period. However, SDP increased body weight gain and feed efficiency during the treatment period. The improved performance over the control group that resulted from feeding a combination of SDP and egg product was primarily dependent upon the SDP. In the third week, a trend occurred for improved performance of pigs fed the egg product compared with those fed 4% SDP; however, the difference was not significant. During this same period, pigs previously fed SDP gained weight slower and consumed less feed than those that had not been fed SDP. Therefore, the response to SDP was partially lost when it was removed from the diet. In summary, the outcome of this study demonstrated that inedible egg product was an adequate source of protein for the weanling pig but did not provide measurable improvements over the control diet. Inedible egg product did not have an additive effect when combined with SDP. The improved feed efficiency associated with SDP resulted in increased weanling pig growth