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Direct Measurement of Vanadium Crossover in an Operating Vanadium Redox Flow Battery
Measurements of Vanadium diffusion coefficients for transport across cation exchange membranes using dialysis cells have been reported in the literature. However, to date direct measurement of crossover coefficients in an operating Vanadium redox flow battery (VRB) cell have not been reported. Results are reported in this paper on experiments utilizing a special VRB cell which allows measurement of Vanadium ion transport across ion exchange membranes with and without the presence of current. The cell utilizes two additional flow regions which collect Vanadium ions which diffuse from the positive and negative half cells. The effects of the magnitude and direction of electrical current on transport can be measured directly with this cell. We observe that transport is greatly enhanced when the direction of the hydrogen ion flux is in the same direction as the density gradient driven vanadium flux and suppressed when the hydrogen ion flux is in the opposite direction. The cell has been used to of investigate the effects on transport of current densities up to 900 mA/cm(2).US Department of Energy ARPA-E program DE-AR00000149Materials Science and Engineerin
Aspects of Dark Matter Annihilation in Cosmology
Cosmic microwave background (CMB) constraints on dark matter annihilation are
a uniquely powerful tool in the quest to understand the nature of dark matter.
Annihilation of dark matter to Standard Model particles between recombination
and reionization heats baryons, ionizes neutral hydrogen, and alters the CMB
visibility function. Surprisingly, CMB bounds on dark matter annihilation are
not expected to improve significantly with the dramatic improvements in
sensitivity expected in future cosmological surveys. In this paper, we will
present a simple physical description of the origin of the CMB constraints and
explain why they are nearly saturated by current observations. The essential
feature is that dark matter annihilation primarily affects the ionization
fraction which can only increase substantially at times when the universe was
neutral. The resulting change to the CMB occurs on large angular scales and
leads to a phenomenology similar to that of the optical depth to reionization.
We will demonstrate this impact on the CMB both analytically and numerically.
Finally, we will discuss the additional impact that changing the ionization
fraction has on large scale structure.Comment: 22 pages, 11 figure
Comparison of hot wire/laser velocimeter turbulence intensity measurements
The question of whether a random measure of particle velocities yields a good statistical estimate of the stationary condition of the turbulence flow field was investigated by comparing hot-wire and laser velocimeter turbulence intensity measurements. Great care was taken to insure that the instrument precision of both the laser velocimeter and hot wire was maximized. In this attempt to reduce the measurement uncertainties in the hot wire, direct digitization of the analog output signal was performed with point-by-point conversion to velocity through a spline fit calibration curve and the turbulence intensity function was calculated statistically. Frequent calibrations of the hot wire were performed using the laser velocimeter as the velocity standard to account for the presence of the small seed particles in the air flow and signal drift in the hot wire
Lensing reconstruction from line intensity maps: the impact of gravitational nonlinearity
We investigate the detection prospects for gravitational lensing of
three-dimensional maps from upcoming line intensity surveys, focusing in
particular on the impact of gravitational nonlinearities on standard quadratic
lensing estimators. Using perturbation theory, we show that these
nonlinearities can provide a significant contaminant to lensing reconstruction,
even for observations at reionization-era redshifts. However, we show how this
contamination can be mitigated with the use of a "bias-hardened" estimator.
Along the way, we present an estimator for reconstructing long-wavelength
density modes, in the spirit of the "tidal reconstruction" technique that has
been proposed elsewhere, and discuss the dominant biases on this estimator.
After applying bias-hardening, we find that a detection of the lensing
potential power spectrum will still be challenging for the first phase of
SKA-Low, CHIME, and HIRAX, with gravitational nonlinearities decreasing the
signal to noise by a factor of a few compared to forecasts that ignore these
effects. On the other hand, cross-correlations between lensing and galaxy
clustering or cosmic shear from a large photometric survey look promising,
provided that systematics can be sufficiently controlled. We reach similar
conclusions for a single-dish survey inspired by CII measurements planned for
CCAT-prime, suggesting that lensing is an interesting science target not just
for 21cm surveys, but also for intensity maps of other lines.Comment: 40+18 pages, 13 figures, 5 tables. v2: JCAP published version, with
typos fixed and clarifications adde
A CONJOINT ANALYSIS OF NEW FOOD PRODUCTS PROCESSED FROM UNDERUTILIZED SMALL CRAWFISH
Attributes for two value-added seafood products derived from underutilized crawfish are analyzed using conjoint data from seafood restaurants in the southern region of the United States. Preferences for the products' form, price, and flavor attributes were tested. Statistical tests revealed that the attribute interactions were not significant, and part-worth utilities for all main effects were estimated using an additive preference model. Results indicate that the new crawfish products should be marketed as a high-quality fresh soup base or seafood stuffing, priced between 30% and 50% of the cost of fresh crawfish tail meat.Conjoint analysis, Seafood, Value added, Marketing,
Developments in aquatic microbiology
Major discoveries in marine microbiology over the past 4-5 decades have resulted in the recognition of bacteria as a major biomass component of marine food webs. Such discoveries include chemosynthetic activities in deep-ocean ecosystems, survival processes in oligotrophic waters, and the role of microorganisms in food webs coupled with symbiotic relationships and energy flow. Many discoveries can be attributed to innovative methodologies, including radioisotopes, immunofluorescent-epifluorescent analysis, and flow cytometry. The latter has shown the key role of marine viruses in marine system energetics. Studies of the components of the “microbial loop” have shown the significance of various phagotrophic processes involved in grazing by microinvertebrates. Microbial activities and dissolved organic carbon are closely coupled with the dynamics of fluctuating water masses. New biotechnological approaches and the use of molecular biology techniques still provide new and relevant information on the role of microorganisms in oceanic and estuarine environments. International interdisciplinary studies have explored ecological aspects of marine microorganisms and their significance in biocomplexity. Studies on the origins of both life and ecosystems now focus on microbiological processes in the marine environment. This paper describes earlier and recent discoveries in marine (aquatic) microbiology and the trends for future work, emphasizing improvements in methodology as major catalysts for the progress of this broadly-based field
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