Characterization of thermochemical properties of Al nanoparticle and NiO nanowire composites
Thermochemical properties and microstructures of the composite of Al nanoparticles and NiO nanowires were characterized. The nanowires were synthesized using a hydrothermal method and were mixed with these nanoparticles by sonication. Electron microscopic images of these composites showed dispersed NiO nanowires decorated with Al nanoparticles. Thermal analysis suggests the influence of NiO mass ratio was insignificant with regard to the onset temperature of the observed thermite reaction, although energy release values changed dramatically with varying NiO ratios. Reaction products from the fuel-rich composites were found to include elemental Al and Ni, Al2O3, and AlNi. The production of the AlNi phase, confirmed by an ab initio molecular dynamics simulation, was associated with the formation of some metallic liquid spheres from the thermite reaction.
Comparative Study of the Oxidation of NiAl(100) by Molecular Oxygen and Water Vapor Using Ambient-Pressure X-ray Photoelectron Spectroscopy.
The oxidation behavior of NiAl(100) by molecular oxygen and water vapor under a near-ambient pressure of 0.2 Torr is monitored using ambient-pressure X-ray photoelectron spectroscopy. O2 exposure leads to the selective oxidation of Al at temperatures ranging from 40 to 500 °C. By contrast, H2O exposure results in the selective oxidation of Al at 40 and 200 °C, and increasing the oxidation temperature above 300 °C leads to simultaneous formation of both Al and Ni oxides. These results demonstrate that the O2 oxidation forms a nearly stoichiometric Al2O3 structure that provides improved protection to the metallic substrate by barring the outward diffusion of metals. By contrast, the H2O oxidation results in the formation of a defective oxide layer that allows outward diffusion of Ni at elevated temperatures for simultaneous NiO formation.
Similarities in protozoan and flatworm habituation behavior.
ONE problem in the study of habituation in protozoa is that similar results, given the same experimental manipulations, may not be obtained in metazoa. I shall compare habituation behaviour in the protozoan Spirostomum with that in the micrometazoan Rhabdocoel flatworm Stenostomum; it remains to be shown whether there is a correspondence between protozoa and metazoa both in behaviour and in their underlying chemical processes. Both these organisms contract in response to mechanical and touch stimuli: when subjected to repeated stimulation, they habituate1. Furthermore, the more intense the stimulus, the longer it takes for habituation to occur1.