Phototactic supersmarticles

Smarticles or smart active particles are small robots equipped with only basic movement and sensing abilities that are incapable of rotating or displacing individually. We study the ensemble behavior of smarticles, i.e., the behavior a collective of these very simple computational elements can achieve, and how such behavior can be implemented using minimal programming. We show that an ensemble of smarticles constrained to remain close to one another (which we call a supersmarticle), achieves directed locomotion toward or away from a light source, a phenomenon known as phototaxing. We present experimental and theoretical models of phototactic supersmarticles that collectively move with a directed displacement in response to light. The motion of the supersmarticle is stochastic, performing approximate free diffusion, and is a result of chaotic interactions among smarticles. The system can be directed by introducing asymmetries among the individual smarticle’s behavior, in our case, by varying activity levels in response to light, resulting in supersmarticle-biased motion.     

Effects of coal syngas impurities on anodes of solid oxide fuel cells

A literature review is conducted to summarize the studies on the identification of impurities in coal syngas and their effects on the performance of Ni-yttria stabilized zirconia (Ni-YSZ) anode of solid oxide fuel cells (SOFCs). Coal syngas typically contains major species, CO, H₂, CO₂, H₂O, CH₄, N₂, and H₂S as well as trace impurities. Thermodynamic equilibrium calculations have indicated that trace impurities species such as Be, Cr, K, Na, and V in the coal syngas form condensed phases under warm gas cleanup conditions and can be effectively removed by the cleanup processes. For meaningful data comparison, a practical parameter is formulated to quantify the level of degradation normalized with respect to the relevant experimental parameters. Experimental results show that the existence of Hg, Si, Zn and NH₃ in the coal syngas does not significantly affect the performance of the Ni-YSZ anode. The presence of Cd and Se in the syngas impacts the SOFC anode performance to some extent. Impurity species such as Cl, Sb, As, and P cause severe cell voltage degradation due to attack on the Ni-YSZ anode. Sb, As and P have the potential to react with Ni to form secondary phases in the Ni-YSZ anode, which deteriorate the catalytic activity of the anode.     

Sex differences in spatial ability and activity in two vole species (Microtus ochrogaster and M. pennsylvanicus).

The hypothesis that sex differences in maze learning result from sex differences in activity was tested with wild-caught prairie (Microtus ochrogaster) and meadow (M. pennsylvanicus) voles. For 38 voles error production and activity were simultaneously measured in a series of 7 symmetrical mazes. Repeated-measures analyses of variance (ANOVAs) examined species, sex, maze, and interaction effects for 3 dependent variables: errors, activity, and errors/activity. The pattern of significant effects was very different for the errors and activity ANOVAs, which suggests that differential activity cannot explain differential error rates. In contrast, the pattern of effects was very similar for errors and errors/activity ANOVAs, which suggests that controls for activity do not remove differences in error production. These results fail to support the activity hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polyfluoroalkyl compounds in free-ranging bottlenose dolphins (Tursiops truncatus) from the Gulf of Mexico and the Atlantic Ocean

Polyfluoroalkyl compounds (PFAs) have been used for decades in industrial and commercial products and are now detected worldwide. Concentrations of two major PFA groups, carboxylic acids (PFCAs) and sulfonic acids (PFSAs), were assessed in plasma of bottlenose dolphins from the Gulf of Mexico (Sarasota Bay, FL) and the Atlantic Ocean (Delaware Bay, NJ, Charleston, SC, Indian River Lagoon (IRL), FL, and Bermuda). Eight PFAs were detected in the plasma of all dolphins. Perfluorooctane sulfonate (PFOS) was the predominant compound at all locations (range from 49 ng/g wet weight (w.w.) in dolphins from Bermuda to 1171 ng/g w.w. in plasma of animals from Charleston). Sum of PFA concentrations were significantly higher in animals from Charleston compared to IRL, Sarasota Bay, and Bermuda. Concentrations of several PFAs were negatively associated with age in animals from IRL and Charleston. No differences between gender were observed for all compounds at all locations. An increase in PFA concentrations was associated with a decrease of blubber thickness in animals from Sarasota Bay and IRL. Fluorotelomer 8:2 and 10:2 unsaturated carboxylic acids (FTUCAs), known degradation products of fluorotelomer alcohols and suspected precursors to PFCAs, were detected for the first time at low concentrations in plasma of dolphins.