Comparative study of Ga2O3 : Dy3+ phosphors prepared by three methods

Trivalent dysprosium (Dy3+)-activated beta-gallium oxide (beta-Ga2O3) phosphors were synthesized by solid-state (SS), coprecipitation (CP), and citrate gel (CG) methods, respectively. The resulting beta-Ga2O3:Dy3+ phosphors were well characterized by X-ray diffraction, field-emission scanning electron microscopy (FESEM), and by photoluminescence and cathodoluminescence spectra. The phosphors prepared by different methods show different luminescence properties under the excitation of UV and low-voltage cathode rays. There exists an energy transfer from the beta-Ga2O3 host lattices to Dy3+, and the energy transfer efficiency was higher in the CG-derived phosphors than those of the SS- and CP-derived phosphors. Factors influencing the intensity of luminescence and the energy transfer efficiency from beta-Ga2O3 host to Dy3+ in beta-Ga2O3:Dy3+ phosphors were investigated in detail. It is shown that the CG method is the most respected process for the preparation of beta-Ga2O3:Dy3+ phosphors.

Handbuch der Radiologie, unter Mitwirkung von A. Bestelmeyer,

Mode of access: Internet.

Fundamental research on raw materials used for electron emissivity on indirectly heated cathodes. Interim technical report.

1st has subtitle: First quarterly progress report; 2d-6th, Second-Sixth quarterly periodic status report.

Performance of the CMS cathode strip chambers with cosmic rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47μm to 243μm. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns. © 2010 IOP Publishing Ltd and SISSA.

Röntgen rays;

Bibliography: p. 74.

Unwrapping an ancient Egyptian mummy using x-rays

This article describes a project to unwrap an ancient Egyptian mummy using X-ray computed tomography (CT). About 600 X-ray CT images were obtained through the mummified body of a female named Tjetmutjengebtiu (or Jeni for short), who was a singer in the great temple of Karnak in Egypt during the 22nd dynasty (c. 945-715 BC). The X-ray CT images reveal details of the remains of body organs, wrappings and jewellery. 3D reconstructions of Jeni’s teeth suggest that she was probably only around 20 years old when she died, although the cause of death cannot be ascertained from the CT scans. The CT images were used to build a 3D model of Jeni’s head which enabled an artist to paint a picture of what Jeni may have looked like during life. A PowerPoint presentation and movie clips are provided as supplementary material that may be useful for teaching.

Ray’s night out : A new iPhone app for addressing alcohol misuse in young people

Up to 30% of young people drink at risky levels at least weekly. Yet, many do not view their alcohol use as problematic and focus only on its enjoyment and socialization benefits. Innovative, youth-friendly and highly accessible ways of delivering preventative health messages are required. This paper describes the design, development and prototype testing of ‘Ray’s Night Out’ a new iPhone application for promoting harm minimisation and controlled drinking strategies in young people. Two participatory design workshops were conducted with 5 young people to explore how technology could be used to enhance a good night out drinking. Four existing iPhone alcohol apps were reviewed. Five young people conducted initial prototype testing to refine app content and interface design. Final prototype testing was conducted with 10 young people. Prototype testing indicated young people had a very positive response to the Ray animated character and rated the app highly on aesthetics, engagement, content, functionality, usefulness and youth relevance. The Ray app provides a youth friendly approach to addressing alcohol misuse in young people. The impact of the Ray app on young people’s alcohol use knowledge, attitudes and behaviours is currently being evaluated.

Magnetic control of breakdown : toward energy-efficient hollow-cathode magnetron discharges

Characteristics of electrical breakdown of a planar magnetron enhanced with an electromagnet and a hollow-cathode structure, are studied experimentally and numerically. At lower pressures the breakdown voltage shows a dependence on the applied magnetic field, and the voltage necessary to achieve the self-sustained discharge regime can be significantly reduced. At higher pressures, the dependence is less sensitive to the magnetic field magnitude and shows a tendency of increased breakdown voltage at the stronger magnetic fields. A model of the magnetron discharge breakdown is developed with the background gas pressure and the magnetic field used as parameters. The model describes the motion of electrons, which gain energy by passing the electric field across the magnetic field and undergo collisions with neutrals, thus generating new bulk electrons. The electrons are in turn accelerated in the electric field and effectively ionize a sufficient amount of neutrals to enable the discharge self-sustainment regime. The model is based on the assumption about the combined classical and near-wall mechanisms of electron conductivity across the magnetic field, and is consistent with the experimental results. The obtained results represent a significant advance toward energy-efficient multipurpose magnetron discharges.

How useful are x-rays in severe paediatric cervical spinal injuries?

INTRODUCTION Radiological evaluation of the paediatric cervical spine can be a challenge due to the normal anatomic variants and injuries that are unique to children. We aimed to identify the usefulness of plain X-rays in comparison with CT and MRI in diagnosing Paediatric cervical spinal injuries. METHODS Retrospective review of imaging studies of children diagnosed with paediatric cervical spine injuries who had presented to two tertiary hospitals in Queensland. RESULTS There were 38 patients with 18 male and 20 female .The mean age was 8.6 years. Plain Cervical Spine X-rays (3views, AP lateral and open mouth views) were done in 34 patients. The remaining 8 children had a suspected head injury and hence had CT scans of their neck done at the time of CT head scan. Of these images taken, X-rays were diagnostic in 28 (82%) patients. CONCLUSION X- Rays still have a role to play in the diagnosis of pediatric cervical spinal injuries and should be considered as the first line in fully conscious patients and their usefulness should not be overlooked in light of the newer imaging modalities.

Generalized pencils of rays in statistical wave optics

The recently introduced generalized pencil of Sudarshan which gives an exact ray picture of wave optics is analysed in some situations of interest to wave optics. A relationship between ray dispersion and statistical inhomogeneity of the field is obtained. A paraxial approximation which preserves the rectilinear propagation character of the generalized pencils is presented. Under this approximation the pencils can be computed directly from the field conditions on a plane, without the necessity to compute the cross-spectral density function in the entire space as an intermediate quantity. The paraxial results are illustrated with examples. The pencils are shown to exhibit an interesting scaling behaviour in the far-zone. This scaling leads to a natural generalization of the Fraunhofer range criterion and of the classical van Cittert-Zernike theorem to planar sources of arbitrary state of coherence. The recently derived results of radiometry with partially coherent sources are shown to be simple consequences of this scaling.

A review of the application of molecular genetics for fisheries management and conservation of sharks and rays

Since the first investigation 25 years ago, the application of genetic tools to address ecological and evolutionary questions in elasmobranch studies has greatly expanded. Major developments in genetic theory as well as in the availability, cost effectiveness and resolution of genetic markers were instrumental for particularly rapid progress over the last 10 years. Genetic studies of elasmobranchs are of direct importance and have application to fisheries management and conservation issues such as the definition of management units and identification of species from fins. In the future, increased application of the most recent and emerging technologies will enable accelerated genetic data production and the development of new markers at reduced costs, paving the way for a paradigm shift from gene to genome-scale research, and more focus on adaptive rather than just neutral variation. Current literature is reviewed in six fields of elasmobranch molecular genetics relevant to fisheries and conservation management (species identification, phylogeography, philopatry, genetic effective population size, molecular evolutionary rate and emerging methods). Where possible, examples from the Indo-Pacific region, which has been underrepresented in previous reviews, are emphasized within a global perspective. (C) 2012 The Authors Journal of Fish Biology (C) 2012 The Fisheries Society of the British Isles

Rapid synthetic routes to prepare LiNi1/3Mn1/3Co1/3O2 as a high voltage, high-capacity Li-ion battery cathode material

LiNi1/3Mn1/3Co1/3O2, a high voltage and high-capacity cathode material for Li-ion batteries, has been synthesized by three different rapid synthetic methods. viz. nitrate-melt decomposition, combustion and sol-gel methods. The first two methods are ultra rapid and a time period as small as 15 min is sufficient to prepare nano-crystalline LiNi1/3Mn1/3Co1/3O2. The processing parameters in obtaining the best performing materials are optimized for each process and their electrochemical performance is evaluated in Li-ion cells. The combustion-derived LiNi1/3Mn1/3Co1/3O2 sample exhibits large extent of cation mixing (10%) while the other two methods yield LiNi1/3Mn1/3Co1/3O2 with cation mixing <5%. LiNi1/3Mn1/3Co1/3O2 prepared by nitrate-melt decomposition method exhibits superior performance as Li-ion battery cathode material.

A Methanol-Tolerant Carbon-Supported Pt-Au Alloy Cathode Catalyst for Direct Methanol Fuel Cells and Its Evaluation by DFT

A Pt-Au alloy catalyst of varying compositions is prepared by codeposition of Pt and Au nanoparticles onto a carbon support to evaluate its electrocatalytic activity toward an oxygen reduction reaction (ORR) with methanol tolerance in direct methanol fuel cells. The optimum atomic weight ratio of Pt to Au in the carbon-supported Pt-Au alloy (Pt-Au/C) as established by cell polarization, linear-sweep voltammetry (LSV), and cyclic voltammetry (CV) studies is determined to be 2:1. A direct methanol fuel cell (DMFC) comprising a carbon-supported Pt-Au (2:1) alloy as the cathode catalyst delivers a peak power density of 120 mW/cm2 at 70 °C in contrast to the peak power density value of 80 mW/cm2 delivered by the DMFC with carbon-supported Pt catalyst operating under identical conditions. Density functional theory (DFT) calculations on a small model cluster reflect electron transfer from Pt to Au within the alloy to be responsible for the synergistic promotion of the oxygen-reduction reaction on a Pt-Au electrode.