http://hdl.handle.net/10453/156 Thu, 23 May 2013 17:00:59 GMT 2013-05-23T17:00:59Z http://hdl.handle.net/10453/17983 Wet Mars implications of revised scaling calculations for Evros Vallis Caprarelli Graziella; Wang Bu In this paper we report the results of our investigation of Evros Vallis, a martian late Noachian dendritic valley network centered at similar to 12 degrees E, 12 degrees S. The study area is located SSW of Schiaparelli and SE relative to Meridiani Planum. After establishment of the valley system, the region underwent extensive erosion and tectonic activity, which partly obliterated and modified Evros Vallis's original features. We used Mars Global Surveyor Mars Orbiter Laser Altimeter, Mars Odyssey Thermal Emission Imaging System, and Mars Express High Resolution Stereo Camera imagery and altimetry data to carry out observations and morphometric analysis of the system, and applied network scaling parameters to our measurements of valley widths, slopes, lengths and drainage areas. We obtained the following results: (a) Hack's law exponent n-1.02; (b) width-area scaling exponent b-0.21; and (c) slope-area scaling exponent theta=0.23. These values are different from those previously derived from analysis of the eastern extent of the valley system. We found that network scaling is not applicable to the investigation of Evros Vallis, a conclusion that may be relevant also to other martian network valleys. The concave-up 790 km-long profile of the main valley suggests that a classic equilibrium status was reached. Our findings are in agreement with models of a warmer and wetter martian climate at the end of the Noachian. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10453/17983 2012-01-01T00:00:00Z http://hdl.handle.net/10453/17984 Development of carbon nanotube-reinforced hydroxyapatite bioceramics Kealley Catherine; Ben-Nissan Besim; Van Riessen A.; Elcombe M. This paper reports development of a production method to produce a composite material that is biocompatible, with high mechanical strength and resilience. The chemical precipitation conditions necessary for the production of synthetic hydroxyapatite (HAp) were determined and include pH, temperature and rate of reaction. A gas phase purification method was optimised to remove the soot impurity from the nanotubes, with transmission electron microscopy showing the preservation of the carbon nanotubes. Subsequent development of chemical and physical reinforcement techniques to produce a HAp + carbon nanotube composite material have been trialled. Hot isostatically pressed samples showed excellent densification and strength. Sun, 01 Jan 2006 00:00:00 GMT http://hdl.handle.net/10453/17984 2006-01-01T00:00:00Z http://hdl.handle.net/10453/17986 Glycothermal synthesis of assembled vanadium oxide Fu Haitao; Jiang Xuchuan; Yang Xiaohong; Yu Aibing; Su Dawei; Wang Guoxiu This study demonstrates a facile but effective glycothermal method to synthesize vanadium oxide nanostructures for gas sensing detection. In this method, sodium orthovanadate was first dispersed and heated in ethylene glycol at 120-180 degrees C for a few hours, and then the precipitates were collected, rinsed, and sintered at high temperatures (e.g., 600 degrees C) for V2O5 in air and V2O3 in nitrogen, respectively. The as-prepared vanadium oxide particles are nanorods (200 nm x 1 mu m) and can assemble into microspheres or urchin-like structures with a diameter of similar to 3 mu m. The experimental parameters (temperature, time, and surfactants) and the formation mechanisms were investigated by various advanced techniques, such as transmission electron microscope, scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and thermo-gravimetric analysis. Finally, the V2O5 nanoparticles were tested for sensing detection of gas species of acetone, isopropanol, and ammonia. The microurchin structures show higher sensing performance than the nanorods. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10453/17986 2012-01-01T00:00:00Z http://hdl.handle.net/10453/17985 Graphene-supported SnO2 nanoparticles prepared by a solvothermal approach Wang Bei; Su Dawei; Park Jinsoo; Ahn Hyojun; Wang Guoxiu SnO2 nanoparticles were dispersed on graphene nanosheets through a solvothermal approach using ethylene glycol as the solvent. The uniform distribution of SnO2 nanoparticles on graphene nanosheets has been confirmed by scanning electron microscopy and transmission electron microscopy. The particle size of SnO2 was determined to be around 5 nm. The assynthesized SnO2/graphene nanocomposite exhibited an enhanced electrochemical performance in lithium-ion batteries, compared with bare graphene nanosheets and bare SnO2 nanoparticles. The SnO2/graphene nanocomposite electrode delivered a reversible lithium storage capacity of 830 mAh gâ¿¿1 and a stable cyclability up to 100 cycles. The excellent electrochemical properties of this graphene-supported nanocomposite could be attributed to the insertion of nanoparticles between graphene nanolayers and the optimized nanoparticles distribution on graphene nanosheets. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10453/17985 2012-01-01T00:00:00Z