669 research outputs found

    Nanotransfer Printing of Organic and Carbon Nanotube Thin-Film Transistors on Plastic Substrates

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    A printing process for high-resolution transfer of all components for organic electronic devices on plastic substrates has been developed and demonstrated for pentacene (Pn), poly (3-hexylthiophene) and carbon nanotube (CNT) thin-film transistors (TFTs). The nanotransfer printing process allows fabrication of an entire device without exposing any component to incompatible processes and with reduced need for special chemical preparation of transfer or device substrates. Devices on plastic substrates include a Pn TFT with a saturation, field-effect mobility of 0.09 cm^2 (Vs)^-1 and on/off ratio approximately 10^4 and a CNT TFT which exhibits ambipolar behavior and no hysteresis.Comment: to appear in Applied Physics Letter

    An Experimental Study of the Production of Metallic Impregnations and Coatings -- a Vacuum Process

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    The purpose of this study undertaken was threefold, (1) to design and construct an experimental vacuum apparatus to produce a metal impregnated or coated material; (2) to study some of the variables which affect the process; then (3) to examine the physical characteristics of the resultant materials. Described herein is the development and operation of a vacuum system capable of producing conditions to permit the evaporation of metals to impregnate and coat various materials. The fundamental principle involved in this process is that a rarified atmosphere reduces the temperature required for metal evaporation and protects the metal vapor from reacting with the contaminants as it is transferred to and deposited on a receiving material

    Dynamic tissue analysis using time- and wavelength-resolved fluorescence spectroscopy for atherosclerosis diagnosis

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    Simultaneous time- and wavelength-resolved fluorescence spectroscopy (STWRFS) was developed and tested for the dynamic characterization of atherosclerotic tissue ex vivo and arterial vessels in vivo. Autofluorescence, induced by a 337 nm, 700 ps pulsed laser, was split to three wavelength sub-bands using dichroic filters, with each sub-band coupled into a different length of optical fiber for temporal separation. STWRFS allows for fast recording/analysis (few microseconds) of time-resolved fluorescence emission in these sub-bands and rapid scanning. Distinct compositions of excised human atherosclerotic aorta were clearly discriminated over scanning lengths of several centimeters based on fluorescence lifetime and the intensity ratio between 390 and 452 nm. Operation of STWRFS blood flow was further validated in pig femoral arteries in vivo using a single-fiber probe integrated with an ultrasound imaging catheter. Current results demonstrate the potential of STWRFS as a tool for real-time optical characterization of arterial tissue composition and for atherosclerosis research and diagnosis

    Volatile Analysis by Pyrolysis of Regolith for Planetary Resource Exploration

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    The extraction and identification of volatile resources that could be utilized by humans including water, oxygen, noble gases, and hydrocarbons on the Moon, Mars, and small planetary bodies will be critical for future long-term human exploration of these objects. Vacuum pyrolysis at elevated temperatures has been shown to be an efficient way to release volatiles trapped inside solid samples. In order to maximize the extraction of volatiles, including oxygen and noble gases from the breakdown of minerals, a pyrolysis temperature of 1400 C or higher is required, which greatly exceeds the maximum temperatures of current state-of-the-art flight pyrolysis instruments. Here we report on the recent optimization and field testing results of a high temperature pyrolysis oven and sample manipulation system coupled to a mass spectrometer instrument called Volatile Analysis by Pyrolysis of Regolith (VAPoR). VAPoR is capable of heating solid samples under vacuum to temperatures above 1300 C and determining the composition of volatiles released as a function of temperature

    Peer Health Coach Training Practicum: Evidence from a Flipped Classroom

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    Health coaching is a popular and effective method to assist individuals in gaining motivation to engage in healthy lifestyle behavior changes. The utility has led to an increased demand for trained individuals within the health care field. A new flipped classroom practicum course was developed to offer undergraduate students the opportunity to learn a foundational skill called motivational interviewing (MI) commonly used in health coaching. The 16-week, 2-credit course (led by three trained, graduate student health coaches) consists of online video lectures, in-class activities, experiential training, and supervised practicum experiences in health coaching. The aim of this study is to evaluate the process, impact, and outcomes of this new health coaching practicum. Measures consisted of surveys to assess participant satisfaction and course impact using 6-point Likert scales and were analyzed descriptively (mean ± SD), along with obtaining recorded MI conversations to evaluate fidelity of the training. These preliminary results support the utility of a flipped classroom practicum course designed to teach undergraduate students the skills of MI; however, extended practice with the use of MI may be needed for students to meet all proficiency levels

    Adaptive Variation Regulates the Expression of the Human SGK1 Gene in Response to Stress

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    The Serum and Glucocorticoid-regulated Kinase1 (SGK1) gene is a target of the glucocorticoid receptor (GR) and is central to the stress response in many human tissues. Because environmental stress varies across habitats, we hypothesized that natural selection shaped the geographic distribution of genetic variants regulating the level of SGK1 expression following GR activation. By combining population genetics and molecular biology methods, we identified a variant (rs9493857) with marked allele frequency differences between populations of African and European ancestry and with a strong correlation between allele frequency and latitude in worldwide population samples. This SNP is located in a GR-binding region upstream of SGK1 that was identified using a GR ChIP-chip. SNP rs9493857 also lies within a predicted binding site for Oct1, a transcription factor known to cooperate with the GR in the transactivation of target genes. Using ChIP assays, we show that both GR and Oct1 bind to this region and that the ancestral allele at rs9493857 binds the GR-Oct1 complex more efficiently than the derived allele. Finally, using a reporter gene assay, we demonstrate that the ancestral allele is associated with increased glucocorticoid-dependent gene expression when compared to the derived allele. Our results suggest a novel paradigm in which hormonal responsiveness is modulated by sequence variation in the regulatory regions of nuclear receptor target genes. Identifying such functional variants may shed light on the mechanisms underlying inter-individual variation in response to environmental stressors and to hormonal therapy, as well as in the susceptibility to hormone-dependent diseases

    Validation of vertical ground heat exchanger design methodologies

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    [EN] This work presents a validation of two common methods for designing vertical ground heat exchangers. Both a simulation-based design tool and the ASHRAE handbook design equation are used to find design lengths for four different real systems, using actual experimental data, including building loads as well as physical parameters as inputs. The measured minimum and maximum ground heat exchanger exiting fluid temperatures were used as the design constraint. The simulation-based design tool predicted the borehole length to within 6% in all cases, while the ASHRAE handbook design equation yielded systems with errors from ¿21% to 167%. Most of this error can be explained by the way loads are represented in the ASHRAE handbook equation, with differences in the borehole thermal resistance also playing a smaller part. TheASHRAE handbook equation relies on a very simple load representation; although this allows it to be used as a simple hand calculation, it also precludes it achieving acceptable accuracy. It does not appear to be possible to revise the ASHRAE handbook equation so as to both significantly improve its accuracy and allow its use in a simple hand calculation.Cullin, J.; Spitler, JD.; Montagud Montalvá, CI.; Ruiz Calvo, F.; Rees, S.; Naicker, S.; Konecny, P.... (2015). Validation of vertical ground heat exchanger design methodologies. Science and Technology for the Built Environment. 21(2):137-149. doi:10.1080/10789669.2014.974478S13714921

    The Software for the LRIS on the Keck 10-Meter Telescope

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    We discuss the software for the Low Resolution and Imaging Spectrograph, one of the first light instruments built for the Keck 10-meter telescope. Details of the CCD detector readout scheme, the motor control system, the user interface, the astrometric preparatory software, etc., are given
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