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