36 research outputs found

    Low Cost Silicon Solar Array Project. Feasibility of Low-cost, High-volume Production of Silane and Pyrolysis of Silane to Semiconductor-grade Silicon

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    The presence of copper promotes a more rapid approach to the steady stete operating condition and results in a more consistent reactor effluent composition. The average kinetic and equilibrium yield are unchanged. Incoloy has been identified as the preferred choice of material of construction for the hydrogenation reactor although certain metallurgical changes were noted in samples exposed to the H2/HCl atmosphere at 500 C which indicate the need for more testing

    Low cost silicon solar array project silicon materials task: Establishment of the feasibility of a process capable of low-cost, high volume production of silane (step 1) and the pyrolysis of silane to semiconductor-grade silicon (step 2)

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    A quartz fluid bed reactor capable of operating at temperatures of up to 1000 C was designed, constructed, and successfully operated. During a 30 minute experiment, silane was decomposed within the reactor with no pyrolysis occurring on the reactor wall or on the gas injection system. A hammer mill/roller-crusher system appeared to be the most practical method for producing seed material from bulk silicon. No measurable impurities were detected in the silicon powder produced by the free space reactor, using the cathode layer emission spectroscopic technique. Impurity concentration followed by emission spectroscopic examination of the residue indicated a total impurity level of 2 micrograms/gram. A pellet cast from this powder had an electrical resistivity of 35 to 45 ohm-cm and P-type conductivity

    A Policy Maker’s Guide to Designing Payments for Ecosystem Services

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    Over the past five years, there has been increasing interest around the globe in payment schemes for the provision of ecosystem services, such as water purification, carbon sequestration, flood control, etc. Written for an Asian Development Bank project in China, this report provides a user-friendly guide to designing payments for the provision of ecosystem services. Part I explains the different types of ecosystem services, different ways of assessing their value, and why they are traditionally under-protected by law and policy. This is followed by an analysis of when payments for services are a preferable approach to other policy instruments. Part II explains the design issues underlying payments for services. These include identification of the service as well as potential buyers and sellers, the level of service needed, payment timing, payment type, and risk allocation. Part II contains a detailed analysis of the different types of payment mechanisms, ranging from general subsidy and certification to mitigation and offset payments. Part III explores the challenges to designing a payment scheme. These include the ability to monitor service provision, secure property rights, perverse incentives, supporting institutions, and poverty alleviation

    Why do seniors leave resistance training programs?

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    Elissa Burton,1 Anne-Marie Hill,1 Simone Pettigrew,2 Gill Lewin,3 Liz Bainbridge,1 Kaela Farrier,1 Phil Airey,4 Keith D Hill1 1School of Physiotherapy and Exercise Science, 2School of Psychology and Speech Pathology, 3School of Nursing, Midwifery and Paramedicine, Curtin University, 4Council on the Ageing, Perth, WA, Australia Purpose: The proportion of the population, that is older, is growing at a faster rate than other age groups. Physical activity is important for older people because it assists in living independently. Participating in resistance training on a regular basis (twice weekly) is recommended for older people; yet, fewer than 15% of people over 60 years achieve this level. The aim of this article was to investigate the factors contributing to older people’s decisions to stop participation in a resistance training program.Participants and methods: Participants were older people who had chosen to participate in a structured resistance training program specifically designed for seniors and then after a period of time discontinued. This population received a questionnaire in the mail focused on factors contributing to their cessation of resistance training exercise. Qualitative results were analyzed using inductive content analysis.Results: Fifty-six survey responses were received (average age 71.5 years, SD =9.0; 79% females). Injury, illness, and holidaying were the main reasons for ceasing participation. A small but important number of responses (11%) reported that they considered they were not provided with sufficient support during the resistance training programs.Conclusions: To attract and retain their senior clients, the results indicate that program organizers need to provide tailored support to return to resistance training after injury and offer flexible and individualized services that accommodate older people’s life choices in retirement. Keywords: older people, strength training, gymnasium, retention, agin