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.
Fabrication and kinetics study of nano-Al/NiO thermite film by electrophoretic deposition.
Nano-Al/NiO thermites were successfully prepared as film by electrophoretic deposition (EPD). For the key issue of this EPD, a mixture solvent of ethanol-acetylacetone (1:1 in volume) containing 0.00025 M nitric acid was proved to be a suitable dispersion system for EPD. The kinetics of electrophoretic deposition for both nano-Al and nano-NiO were investigated; the linear relation between deposition weight and deposition time in short time and parabolic relation in prolonged time were observed in both EPDs. The critical transition time between linear deposition kinetics and parabolic deposition kinetics for nano-Al and nano-NiO were 20 and 10 min, respectively. The theoretical calculation of the kinetics of electrophoretic deposition revealed that the equivalence ratio of nano-Al/NiO thermites film would be affected by the behavior of electrophoretic deposition for nano-Al and nano-NiO. The equivalence ratio remained steady when the linear deposition kinetics dominated for both nano-Al and nano-NiO. The equivalence ratio would change with deposition time when deposition kinetics for nano-NiO changed into parabolic kinetics dominated after 10 min. Therefore, the rule was suggested to be suitable for other EPD of bicomposites. We also studied thermodynamic properties of electrophoretic nano-Al/NiO thermites film as well as combustion performance.
Electrophysiological evidence that a subset of midbrain dopamine neurons integrate the reward signal induced by electrical stimulation of the posterior mesencephalon
This study was aimed at determining whether midbrain dopamine (DA) neurons are trans-synaptically activated by rewarding electrical stimulation applied near the midline in the posterior mesencephalon (PM), and in the affirmative, whether the increase in firing was proportional to the rewarding effectiveness of the stimulation. Experiments were performed on male Long-Evans rats trained to lever press to obtain 400 ms trains of cathodal rectangular pulses. Following the training period, curves relating the rates of responding to the stimulation frequencies were determined at two current intensities and reward thresholds were calculated for each animal. Each animal was then anesthetized with urethane (1.2 g/kg, i.p.) and firing rate of DA neurons were recorded before, during, and after each of 50 trains (1 train/3 s) of stimulation to the PM using stimulation parameters that either sustained near threshold responding (rewarding), or failed to sustain responding (non-rewarding), in the behavioral tests. A total of 24 DA cells were recorded from 13 behaviorally trained animals, and of these, 17 (71%) responded to rewarding stimulation by an increase in firing, five (21%) were unresponsive and two (8%) were inhibited. In 12 of the 17 cells that were activated, the increase in firing was proportional to the rewarding effectiveness of the stimulation rather than the total strength of the stimulation. These results provide evidence that a subset of midbrain DA neurons are trans-synaptically activated by rewarding PM stimulation and constitute a second, or subsequent, stage of the reward-relevant pathway that integrates the PM reward signal.