Recent Progress in the Development of Neodymium Doped Ceramic Yttria

Solid-state lasers play a significant role in providing the technology necessary for active remote sensing of the atmosphere. Neodymium doped yttria (Nd:Y2O3) is considered to be an attractive material due to its possible lasing wavelengths of aprrox.914 nm and approx.946 nm for ozone profiling. These wavelengths when frequency tripled can generate UV light at approx.305 nm and approx.315 nm, which is particularly useful for ozone sensing using differential absorption lidar technique. For practical realization of space based UV transmitter technology, ceramic Nd:Y2O3 material is considered to possess great potential. A plasma melting and quenching method has been developed to produce Nd3+ doped powders for consolidation into Nd:Y2O3 ceramic laser materials. This far-from-equilibrium processing methodology allows higher levels of rare earth doping than can be achieved by equilibrium methods. The method comprises of two main steps: (a) plasma melting and quenching to generate dense, and homogeneous doped metastable powders, (b) pressure assisted consolidation of these powders by hot isostatic pressing to make dense nanocomposite ceramics. Using this process, several 1" x 1" ceramic cylinders have been produced. The infrared transmission of undoped Y2O3 ceramics was as high as approx.75% without anti-reflection coating. In the case of Nd:Y2O3 ceramics infrared transmission values of approx.50% were achieved. Furthermore, Nd:Y2O3 samples with dopant concentrations of up to approx.2 at. % were prepared without significant emission quenching

Investigating local growth conditions in the flame synthesis of molybdenum-oxide nanoplates from molybdenum substrates

Molybdenum-oxide nanoplates are grown directly from the surface of molybdenum substrates using a catalyst-free flame synthesis technique. To investigate the effects of oxidizing routes, e.g., from gas-phase O2, H2O, and CO2 as reactants, on the growth and morphology of the molybdenum-oxide nanostructures, quasi-1D counterflow diffusion flames are strategically utilized and probed at specific locations within their flame structures. Moreover, two separate flame structures are compared using different fuels (i.e., methane and hydrogen) and diluted with nitrogen to have near-identical temperature profiles. For example, the H2O oxidizing route is scrutinized by assessing growth at the same elevated temperature locations at the fuel sides of the reaction zones of a CH4 flame (comprising H2O and CO2 as synthesis reactants) and an H2 flame (comprising only H2O as synthesis reactant). The temperature effect on the resultant morphologies are examined at 1280 K, 1500 K, and 1720 K. Single-crystalline MoO2 nanoplates (of thicknesses of 60-80 nm, widths of 200-450 nm, and lengths of 1-2 µm) that are regularly distributed with high-surface-area-exposed packing are obtained at 1720 K on the air side of the CH4 flame (with O2, H2O, and CO2 as synthesis reactants) for 10 min growth durations. Based on the results and Gibbs free energy calculations, the CO2 route is deduced to seed the growth of the nanoplates at the nucleation stage heterogeneously, with subsequent condensation-based growth from volatile intermediate species, such as MoO2(OH)2, playing an important role. With such studies revealing fundamental growth mechanisms, scale-up of the process with different flame configurations is afforded

A New Species of the Basal "Kangaroo'' Balbaroo and a Re-Evaluation of Stem Macropodiform Interrelationships

Exceptionally well-preserved skulls and postcranial elements of a new species of the plesiomorphic stem macropodiform Balbaroo have been recovered from middle Miocene freshwater limestone deposits in the Riversleigh World Heritage Area of northwestern Queensland, Australia. This constitutes the richest intraspecific sample for any currently known basal "kangaroo'', and, along with additional material referred to Balbaroo fangaroo, provides new insights into structural variability within the most prolific archaic macropodiform clade - Balbaridae. Qualitative and metric evaluations of taxonomic boundaries demonstrate that the previously distinct species Nambaroo bullockensis is a junior synonym of B. camfieldensis. Furthermore, coupled Maximum Parsimony and Bayesian phylogenetic analyses reveal that our new Balbaroo remains represent the most derived member of the Balbaroo lineage, and are closely related to the middle Miocene B. camfieldensis, which like most named balbarid species is identifiable only from isolated jaws. The postcranial elements of Balbaroo concur with earlier finds of the stratigraphically oldest balbarid skeleton, Nambaroo gillespieae, and suggest that quadrupedal progression was a primary gait mode as opposed to bipedal saltation. All Balbaroo spp. have low-crowned bilophodont molars, which are typical for browsing herbivores inhabiting the densely forested environments envisaged for middle Miocene northeastern Australia

Implications of a new species of the Oligo-Miocene Kangaroo (Marsupialia : Macropodoidea) Nambaroo from the Riversleigh World Heritage Area, Queensland, Australia

Copyright © 2007 Paleontological Societ

Paesaggi australiani Australian Landscapes

Negli ultimi anni l’Australia ha rappresentato un nuovo luogo d’attrazione, un’inedita frontiera culturale, un’ambita località turistica. Ma spesso i media hanno contribuito a fare di questo paese una meta esotica, identificandola con una terra lontanissima e amena. Questo volume, frutto di una giornata di studi dedicata al paesaggio australiano (organizzata dal Dipartimento di Lingue e Letterature straniere moderne di Bologna insieme alla Monash University di Melbourne), traccia, attraverso i vari interventi, un’immagine meno consueta del continente australiano, ma forse più vicina alla sua più vera natura. Fra i contributi, quelli dei maggiori australianisti attivi nell’accademia italiana, giovani studiosi attenti alla realtà letteraria, cinematografica e artistica degli antipodi e il pittore bolognese Maurizio Bottarelli, magnifico illustratore - tutt’altro che esotizzante o agiografico - della natura australian