• Passivation of III-V Semiconductor Surfaces

      Contreras, Yissel; Muscat, Anthony; Department of Chemical and Environmental Engineering, University of Arizona; Department of Chemical and Environmental Engineering, University of Arizona (2013-11-08)
      Computer processor chips of the last generation are based on silicon, modified to achieve maximum charge mobility to enable fast switching speeds at low power. III-V semiconductors have charge mobilities that are much higher than that of silicon making them suitable candidates for boosting the performance of new electronic devices. However, III-V semiconductors oxidize rapidly in air after oxide etching and the poor quality of the resulting oxide limits device performance. Our goal is to design a liquid-phase process flow to etch the oxide and passivate the surface of III-V semiconductors and to understand the mechanism of layer formation.Self-assembled monolayers of 1-eicosanethiol (ET) dissolved in ethanol, IPA, chloroform, and toluene were deposited on clean InSb(100) surfaces. The InSb passivated surfaces were characterized after 0 to 60 min of exposure to air. Ellipsometry measurements showed a starting overlayer thickness (due to ET, oxides, or both) of about 20 Å in chloroform and from 32 to 35 Å in alcohols and toluene. Surface composition analysis of InSb with X-ray photoelectron spectroscopy after passivation with 0.1 mM ET in ethanol confirmed the presence of ET and showed that oxygen in the Auger region is below detection limits up to 3 min after the passivation. Our results show that a thiol layer on top of a non-oxidized or low-oxide semiconductor surface slows oxygen diffusion in comparison to a surface with no thiol present, making this a promising passivation method of III-V semiconductors.
    • Plant fiber reinforced geopolymer - A green and high performance cementitious material

      Chen, Rui; Ahmari, Saeed; Gregory, Mark; Zhang, Lianyang; Department of Civil Engineering and Engineering Mechanics (2011-11-04)
    • Pollen Foraging Bees Don't Learn Unsaturated Floral Color

      Newman, China Rae; Papaj, Dan; Russell, Avery; Ecology and Evolutionary Biology; Entomology and Insect Science (2016-02-24)
      We investigated whether bees have an innate preference for flowers with saturated pigments and whether experience altered any preference. Preference could be a result of reward quality varying by color morph and/or responses to the petals, anthers, or their combination. Consequently, we gave bees experience on one of four floral configurations created from two color morphs of Solanum tridynanum. We subsequently tested learned preference using an array of all four configurations. Changes in preference as a result of experience were not mediated by anthers, only by petals. Bees that first experienced configurations with purple petals subsequently preferred configurations with purple petals, relative to naïve bees. However, bees that first experienced white petals showed no subsequent change in preference relative to naïve bees. Surprisingly, naïve bees showed no preference for any particular floral configuration. Rather than an innate preference for flowers with more saturated colors, bees are less able to develop a preference for unsaturated types. Because individuals are more able to develop a preference for saturated flowers, these flowers experience greater visitation, and thus greater pollination success, over unsaturated types.
    • PVMirror – A High-Efficiency Solar Module

      Hyatt, Justin; Mrkonich, Jeffrey; Reinhart, Lennon; Taylor, Wyatt; Steward Observatory; College of Optical Sciences; Department of Aerospace and Mechanical Engineering (2016-02-24)
      To make photovoltaics (PV) and concentrated solar thermal power (CSP) more practical forms of alternative energy, creative innovations to current solar energy methods must be employed. The PVMirror – a new technology – is our solution to that problem. The PVMirror combines PV and CSP technologies by splitting the spectrum of sunlight using a dichroic mirror film. Light that is not transmitted to the solar cell is to instead be reflected to a focus, by way of a curved mirror. This hybrid of technologies is competitive, as it is both efficient and affordable compared to many other innovations in renewable energy. The PVMirror is designed to be an easy and cost-effective replacement to the reflectors used in existing CSP plants. Ultimately, we hope to demonstrate this PVMirror technology on a large scale and market it. As validated from interviewing with industry professionals, this technology has the potential to impact the world of solar energy because many industrial companies and utility-scale CSP project developers are interested in pairing CSP and PV to increase efficiency. Currently, using an outdoor sun tracker, we are testing an 18 inch by 18 inch prototype with four solar cells.
    • Queer-Ability: History, Culture, and the Future of the Intersection of LGBTQ and Disability Studies

      Przybylowicz, Stephan Elizander; School of Information Resources & Library Science; Sonoran UCEDD Interdisciplinary Training Program (2011-11-04)
    • Renegotiating the Interface Between the Built and Natural Environments

      Johnson, Nicholas (2011-11-04)
      As human consumption and energy production continue to negatively a ect our environment, a re-conceptualization of our relationship to the wider world becomes a necessary step in the coexistence of humankind and nature. Modern methods of building have sought to establish a universal conception of human comfort that is disconnected from the realities of the speci c and varied climates in which we live. The building envelope is seen as a barrier to nature, a fortress where we have complete control over the parameters of our environment. This degree of control ultimately requires an unlimited source of energy. Through development of emerging material systems and technological integration, this project seeks to create a dialog between interior and exterior environments, recognizing that the two should be connected. This re-envisioned interface responds directly to changing environmental conditions through formal and material adaptations which create a symbiotic relationship between the built and natural worlds
    • Stage of invasion: How do sensitive seedlings respond to buffelgrass?

      Sommers, Pacifica; Ecology and Evolutionary Biology (2011-11-04)
    • Theoretics Into Practice: Dance Documentation and Preservation

      Sheather, Danielle; School of Dance, University of Arizona (2014-11-07)
    • Una revolución escrita: The Mexican-American Anthology

      Collins, Hannah; Department of Spanish & Portuguese, University of Arizona (2014-11-07)
    • Using YouTube to Enhance L2 Listening Skills: Animated Cartoons in the Italian Classroom

      Maranzana, Stefano; University of Arizona (2014-11-07)
      Today’s language teachers find increasing resources online that allow greater variety of authentic material. With the opportunities offered by digital video, the traditional listening comprehension activity has reached new potential for incidental learning and learner’s autonomy (Robin, 2011). While conscious attention is on the message delivered by the audiovisual, learners assimilate new words from context without intending to do so, stimulating incidental vocabulary learning (Carlisle, 2007). Video’s inherent multimodality makes sensory information available in various semiotic codes, allowing to the comprehension of information via separate channels (Guichon & McLornan, 2008). This case study involves three students of advanced Italian at a large American University. It will argue in favor of video cartoons as a valuable tool to foster a constructive environment for the acquisition of the L2 (Bahrani, 2014). Specifically, we will look at British award-winning preschool cartoon Peppa Pig in its Italian version. The rationale for choosing this particular cartoon includes: 5 minutes of episode length, authentic interpersonal language and descriptive prose, slow pace of speech, familiar every-day and humorous stories, free online access and the possibility to activate captions. Furthermore, this cartoon may be used for listening comprehension for the 30 other languages in which it has been translated. Feedback from university-level students confirms the potential of this particular cartoon and will be presented in this poster. Students reported strong motivation due to the low affective filter environment (Rule & Ague, 2005) as well as improvement in areas like vocabulary, pragmatics and idiomatic expressions from contextual clues.
    • Utilizing Variable Transplant Methods on the Endangered Pima Pineapple Cactus (Coryphantha scheeri var. robustispina)

      Berthelette, Gerald; Fehmi, Jeffrey; School of Natural Resources and the Environment (2016-02-24)
      There has been little research carried out which assesses the ability or inability of the Pima pineapple cactus (Coryphantha scheeri var. robustispina) to be transplanted successfully, and what a successful transplant entails. From what little research has been done, experiments have demonstrated low-levels of survival, and determinate variables remain largely unknown. As a result, the U.S. Fish and Wildlife Service (USFWS) does not consider transplanting as a viable conservation measure. This study monitors [a population] of individual Pima pineapple cactus (PPC) transplanted in 2014 and distributed along the natural gas pipeline put in place by Kinder Morgan Inc. southwest of Tucson, Arizona, as well as other data sets from past transplant experiments. This post-transplant monitoring, in addition to a thorough analysis of varying transplant methodology and abiotic variables associated with each site, will be used to develop a framework for analyzing transplant successes for the PPC. Variables assessed during this study will include the influence of supplemental watering, using soil vs. bare root methods, and the number of times an individual is transplanted. With the information gathered from the PPC along the pipeline right-of-way, along with information gathered from historical PPC transplant locations, I will present a predictive model for transplanting success of PPC using a chi-square test with the statistical software package, STATA. Success will show a clear correlation between plant vigor after transplanting and the methodology with which each cactus was moved.