Study and determination of an optimum design for space utilized lithium doped solar cells Quarterly report

Recovery characteristics of electron irradiated, lithium doped, solar cell

Characterisation of a novel reverse-biased PPD CMOS image sensor

A new pinned photodiode (PPD) CMOS image sensor (CIS) has been developed and characterised. The sensor can be fully depleted by means of reverse bias applied to the substrate, and the principle of operation is applicable to very thick sensitive volumes. Additional n-type implants under the pixel p-wells, called Deep Depletion Extension (DDE), have been added in order to eliminate the large parasitic substrate current that would otherwise be present in a normal device. The first prototype has been manufactured on a 18 μm thick, 1000 Ω .cm epitaxial silicon wafers using 180 nm PPD image sensor process at TowerJazz Semiconductor. The chip contains arrays of 10 μm and 5.4 μm pixels, with variations of the shape, size and the depth of the DDE implant. Back-side illuminated (BSI) devices were manufactured in collaboration with Teledyne e2v, and characterised together with the front-side illuminated (FSI) variants. The presented results show that the devices could be reverse-biased without parasitic leakage currents, in good agreement with simulations. The new 10 μm pixels in both BSI and FSI variants exhibit nearly identical photo response to the reference non-modified pixels, as characterised with the photon transfer curve. Different techniques were used to measure the depletion depth in FSI and BSI chips, and the results are consistent with the expected full depletion

Beebots-a-lula, Where's My Honey?: Design Fictions and Beekeeping

The honey bee is a powerful cultural motif that remains an important symbol for the future. Their role as pollinators, alongside a myriad of other species, is critical to the continued diets of humankind. This Future Scenario explores a possible near future where human intervention poses new risks to their survival. Drawing on folklore and contemporary beekeeping practices, Mr Shore's Downfall tells a tale of discovery and loss as a young beekeeper is introduced to the world of honey bees. Three imagined artefacts are revealed through the story and discussed with consideration of their cultural context, desirability and relation to socio-economic factors. Themes from Mr Shore's Downfall are examined, and the potential of writing practice for design fiction practitioners is considered

Zero-energy states in graphene quantum dots and rings

We present exact analytical zero-energy solutions for a class of smooth decaying potentials, showing that the full confinement of charge carriers in electrostatic potentials in graphene quantum dots and rings is indeed possible without recourse to magnetic fields. These exact solutions allow us to draw conclusions on the general requirements for the potential to support fully confined states, including a critical value of the potential strength and spatial extent.Comment: 8 pages, 3 figures, references added, typos corrected, discussion section expande

The Dynamical Implications of Multiple Stellar Formation Events in Galactic Globular Clusters

Various galactic globular clusters display abundance anomalies that affect the morphology of their colour-magnitude diagrams. In this paper we consider the possibility of helium enhancement in the anomalous horizontal branch of NGC 2808. We examine the dynamics of a self-enrichment scenario in which an initial generation of stars with a top-heavy initial mass function enriches the interstellar medium with helium via the low-velocity ejecta of its asymptotic giant branch stars. This enriched medium then produces a second generation of stars which are themselves helium-enriched. We use a direct N-body approach to perform five simulations and conclude that such two-generation clusters are both possible and would not differ significantly from their single-generation counterparts on the basis of dynamics. We find, however, that the stellar populations of such clusters would differ from single-generation clusters with a standard initial mass function and in particular would be enhanced in white dwarf stars. We conclude, at least from the standpoint of dynamics, that two-generation globular clusters are feasible.Comment: 24 pages, 7 figures, 3 tables. Accepted for publication in Ap

Bonding machine for forming a solar array strip

A machine is described for attaching solar cells to a flexable substrate on which printed circuitry has been deposited. The strip is fed through: (1) a station in which solar cells are elevated into engagement with solder pads for the printed circuitry and thereafter heated by an infrared lamp; (2) a station at which flux and solder residue is removed; (3) a station at which electrical performance of the soldered cells is determined; (4) a station at which an encapsulating resin is deposited on the cells; (5) a station at which the encapsulated solar cells are examined for electrical performance; and (6) a final station at which the resulting array is wound on a takeup drum

Towards lensfield: Data management, processing and semantic publication for vernacular e-science

Lensfield is a desktop and filesystem-based tool designed as a “personal data management assistant” for the scientist. It combines distributed version control (DVCS), software transaction memory (STM) and linked open data (LOD) publishing to create a novel data management, processing and publication tool. The application “just looks after” these technologies for the scientist, providing simple interfaces for typical uses. It is built with Clojure and includes macros which define steps in a common workflow. Functions and Java libraries provide facilities for automatic processing of data which is ultimately published as RDF in a web application. The progress of data processing is tracked by a fine-grained data structure that can be serialized to disk, with the potential to include manual steps and programmatic interrupts in largely automated processes through seamless resumption. Flexibility in operation and minimizing barriers to adoption are major design features.This paper was presented at the IEEE eScience conference 2009, hosted by the Oxford eResearch Centre and held at the Kassam Stadium outside Oxford

The Impact of a Short-Term Pharmacology Enrichment Program on Knowledge and Science Attitudes in Precollege Students

As our nation and the global economy place an increased demand for science, technology, engineering, and mathematics (STEM) jobs, science educators must implement innovative approaches to pique precollege student’s interests in these careers. Pharmacology remains a relevant and engaging platform to teach biology and chemistry concepts, and this strategy applied over several months in the formal classroom increases science literacy in high school students. In order to improve the affordability and accessibility of this educational approach, we developed and assessed the impact of a short-term pharmacology day camp, ‘Pills, Potions, and Poisons’ (PPP), on high school students’ science knowledge and attitudes toward science careers. The PPP program was offered annually from 2009 through 2012, and participants spent 6 days learning about pharmacology and careers in the biomedical sciences. All PPP student participants (n=134) completed surveys assessing their basic science knowledge and science attitudes before and after the program. Students achieved significant gains in their science knowledge by the end (Day 6) of the PPP program (from 41% mean test score to 65%; p<0.001). In addition, the majority of participants agreed or strongly agreed that the PPP program positively impacted their attitudes toward science (p<0.001). This study provides evidence that a short-term pharmacology-centered science enrichment program can achieve significant gains in participant’s science knowledge as well as motivation and confidence towards science careers. Moreover, we report benefits experienced by the undergraduate, graduate, and professional pharmacy student teaching assistants (TAs, n=10) who reported improved communication skills and an increased interest in future educational work.   Type: Original Researc