27 research outputs found

    Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses

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    The capacity of simulated high-level radioactive waste borosilicate glasses to incorporate sulfate has been studied as a function of glass composition. Combined Raman, 57Fe Mössbauer and literature evidence supports the attribution of coordination numbers and oxidation states of constituent cations for the purposes of modelling, and results confirm the validity of correlating sulfate incorporation in multicomponent borosilicate radioactive waste glasses with different models. A strong compositional dependency is observed and this can be described by an inverse linear relationship between incorporated sulfate (mol% SO42−) and total cation field strength index of the glass, Σ(z/a2), with a high goodness-of-fit (R2 ≈ 0.950). Similar relationships are also obtained if theoretical optical basicity, Λth (R2 ≈ 0.930) or non-bridging oxygen per tetrahedron ratio, NBO/T (R2 ≈ 0.919), are used. Results support the application of these models, and in particular Σ(z/a2), as predictive tools to aid the development of new glass compositions with enhanced sulfate capacities

    Chemical imaging of InGaAs/InAlAs quantum wells

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    We have applied high resolution chemical imaging in a transmission electron microscope to study compositional variations across InGaAs/InAlAs double quantum well structures. The structures of interest are grown on an InP substrate and consist of two 40 angstroms layers of InGaAs separated by 20 angstroms of InAlAs. For this (InGa)x(InAl)1-xAs system, we have been able to obtain compositional information with an accuracy of about 20% and a maximum spatial resolution of 1/2Ã?1/2 unit cell. The results clearly show irregularities on a monatomic scale

    The composition and structure of InGaAs/InAlAs interfaces at the monatomic scale

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    We have applied high-resolution chemical imaging in a transmission electron microscope to study compositional variations across an InGaAs/InAlAs double quantum well structure in the (100) orientation. The structures of interest are grown on an InP support and consist of two 40 � layers of InGaAs separated by 20 � of InAlAs. For this (InGa)x(InAl)1-xAs system, we have obtained compositional information with an accuracy of about 20% and a maximum spatial resolution of 1/4 unit cell. The results clearly show compositional irregularities on a monatomic scale. © 1997 American Institute of Physics

    Prevention and management of non-communicable disease: The IOC consensus statement, Lausanne 2013

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    Morbidity and mortality from preventable, noncommunicable chronic disease (NCD) threatens the health of our populations and our economies. The accumulation of vast amounts of scientific knowledge has done little to change this. New and innovative thinking is essential to foster new creative approaches that leverage and integrate evidence through the support of big data, technology and design thinking. The purpose of this paper is to summarise the results of a consensus meeting on NCD prevention sponsored by the IOC in April 2013. Within the context of advocacy for multifaceted systems change, the IOC's focus is to create solutions that gain traction within healthcare systems. The group of participants attending the meeting achieved consensus on a strategy for the prevention and management of chronic disease that includes the following: (1) Focus on behavioural change as the core component of all clinical programmes for the prevention and management of chronic disease. (2) Establish actual centres to design, implement, study and improve preventive programmes for chronic disease. (3) Use human-centred design in the creation of prevention programmes with an inclination to action, rapid prototyping and multiple iterations. (4) Extend the knowledge and skills of Sports and Exercise Medicine (SEM) professionals to build new programmes for the prevention and treatment of chronic disease focused on physical activity, diet and lifestyle. (5) Mobilise resources and leverage networks to scale and distribute programmes of prevention. True innovation lies in the ability to align thinking around these core strategies to ensure successful implementation of NCD prevention and management programmes within healthcare. The IOC and SEM community are in an ideal position to lead this disruptive change. The outcome of the consensus meeting was the creation of the IOC Non-Communicable Diseases ad hoc Working Group charged with the responsibility of moving this agenda forward
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