29 research outputs found

    Functional carbon nanotubes for electrical conductors

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    Carbon nanotube (CNT) conductors are an enabling technology for advancing the efficacy of sustainable energy systems. In parallel, proactive consideration for each of the phases in the material life cycle can enhance device performance while minimizing unwanted impacts. Increasing the yield of CNTs through advances in synthesis will help reduce the electricity, chemicals, and costs associated with their production. Modifications to the nanoscale morphology (alignment, bundling, density and lower contact resistances) are needed to improve the CNT material properties to meet or exceed those of conventional metallic conductors. Also, a robust evaluation of methods for contacting carbon-based wires is needed when interfacing with metallic contacts. Finally, it\u27s important to begin looking at upstream options for proper treatment of waste streams containing CNT conductors when they reach the end of their useable life. Therefore, the subject of this dissertation focuses on the development of functional CNT conductors and considers approaches to improve each phase of their life cycle. Specifically, progress towards using more efficient catalysts in the laser vaporization process has led to a 50% increase in SWCNT yield and simplified the purification procedure. The use of chemical dopants such as KAuCl4 has increased the electrical conductivity up to 1x106 S/m which is over an order of magnitude higher than the pre-doping baseline value. Alternatively, chlorosulfonic acid was used to disperse high weight loadings of SWCNTs and modify the nanoscale morphology through the use of selective coagulation and mechanical extrusions of binder free SWCNT wires. The highly dense and aligned wires have electrical conductivities as high as 4.9x106 S/m and are in agreement with the highest CNT conductivities reported. The ability to contact bulk CNT conductors through ultrasonic welding was demonstrated for the first time and exhibit low carbon-copper contact resistances of 4.3 mΩ-cm2. Finally, a refunctionalization procedure was developed for upcycling end-of-life CNT electrodes from lithium ion anodes. This is the first reported recycling procedure developed for CNT materials and was successful in reducing the direct electricity consumption by 75 % and the volumetric waste generation by 66 % compared to synthesizing new CNT materials. Overall, CNT based conductors have been enhanced at each point in their life cycle the results presented in this dissertation represent a significant step forward towards manufacturing of next generation carbon conductors

    Transcending Boundaries: The Acousmatic Story in the Anthropocene

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    The multiple crises of the Anthropocene include a crisis in sto- rytelling. Amitav Ghosh, for example, has claimed that not only is literary fiction incapable of representing climate change, it is also complicit in its concealment in the broader culture (2016). Ghosh suggests the increasing entwining of image and text brought about by the Internet could lead to a hybridity of form that will free readers from the unhelpful logocentrism of re- cent times. While agreeing with him on both the need for new forms and the importance of hybridity, we argue that he has overlooked the power of sound in storytelling. Drawing on a collaborative work-in-progress about birdsong and loss, we propose the acousmatic story as a response to the challenges of the age and also to an emerging understanding that all sto- ries are entangled in a vast mesh of agencies, both human and other-than-human

    Meaning in life in psychotherapy: The perspective of experienced psychotherapists

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    Objective Our goal was to explore the meaning experienced psychotherapists derive from providing psychotherapy, their beliefs about the role of meaning in life (MIL) in psychotherapy, how they worked with MIL with a client who explicitly presented concerns about MIL, and how they worked with a different client for whom MIL was a secondary and more implicit concern. Method Thirteen experienced psychotherapists were interviewed and data were analyzed using consensual qualitative research. Results Therapists derived self-oriented meaning (e.g., feeling gratified, fulfilled, connected) and other-oriented meaning (helping others, making the world a better place) from providing psychotherapy. They believed that MIL is fundamental and underlies all human concerns, including those brought to therapy. In contrast to the clients who had implicit MIL concerns, clients who explicitly presented MIL concerns were reported to have more interpersonal problems and physical problems, but about the same amount of psychological distress and loss/grief. Therapists used insight-oriented interventions, support, action-oriented interventions, and exploratory interventions to work with MIL with both types of clients, but used more exploratory interventions with implicit than explicit MIL clients. Conclusions MIL is a salient topic for experienced, existentially oriented psychotherapists; they work with MIL extensively with some clients in psychotherapy. We recommend that therapists receive training to work with MIL in therapy, and that they pay attention to MIL concerns when they conduct psychotherapy. We also recommend additional research on MIL in psychotherapy

    Advanced Power Technology Development Activities for Small Satellite Applications

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    NASA Glenn Research Center (GRC) has a long history related to the development of advanced power technology for space applications. This expertise covers the breadth of energy generation (photovoltaics, thermal energy conversion, etc.), energy storage (batteries, fuel cell technology, etc.), power management and distribution, and power systems architecture and analysis. Such advanced technology is now being developed for small satellite and cubesat applications and could have a significant impact on the longevity and capabilities of these missions. A presentation during the Pre-Conference Workshop will focus on various advanced power technologies being developed and demonstrated by NASA, and their possible application within the small satellite community

    Morphological and chemical influences on alumina-supported palladium catalysts active for the gas phase hydrogenation of crotonaldehyde

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    A series of five alumina-supported palladium catalysts have previously been prepared and characterised by a combination of CO chemisorption and infrared spectroscopy. The reactive attributes of these catalysts are examined using the hydrogenation of crotonaldehyde as a test reaction, using a modified infrared gas cell as a batch reactor. Periodic scanning of the infrared spectrum of the gaseous phase present over the Pd/Al2O3 catalysts was used to construct reaction profiles. Four of the catalysts were able to facilitate a 2-stage hydrogenation process (crotonaldehyde → butanal → butanol), whilst one catalyst was totally selective for the first stage hydrogenation process (crotonaldehyde → butanal). Rate coefficients for the first and second stage hydrogenation processes are normalised to the number of surface palladium atoms for the particular catalyst. Correlation of these kinetic parameters as a function of mean particle size indicates the first stage process to be structure insensitive, whilst the second stage hydrogenation is structure sensitive. Chlorine residues associated with the preparative process of one of the catalysts is seen to selectively poison the second stage hydrogenation process for that catalyst. Structure/activity relationships are considered to explain the observed trends
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