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2007

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Articles 121 - 132 of 132

Full-Text Articles in Engineering Science and Materials

Comparative Characterization Of Superconducting Thin Films Fabricated By Different Techniques, Padma Prasuna S. Vemulakonda Jan 2007

Comparative Characterization Of Superconducting Thin Films Fabricated By Different Techniques, Padma Prasuna S. Vemulakonda

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The goal of this thesis is to compare the chemical and compositional profiles, grain structure and critical current densities of superconducting Yttrium Barium Copper Oxide(Y1Ba2Cu3O7-x or YBCO) layers grown by different competing techniques on a variety of substrates and buffer layers. The idea is to check if there can be variation of cationic ratios, impurities, possible diffusion of substrate/buffer layer atoms into the YBCO for different processing methods and microstructures. Pulsed Laser Deposition (PLD), Metal Organic Deposition (MOD) and Metal Organic Chemical Vapor Deposition (MOCVD) films on Ion Beam Assisted Deposited (IBAD)-textured buffer layers and, Rolling Assisted Biaxial textured substrate …

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Oxidation Resistant Coatings On Microcelluar Carbon Foam Using Simple Scalable Techniques, Dakshinamurthy Sharma Nagalingam Jan 2007

Oxidation Resistant Coatings On Microcelluar Carbon Foam Using Simple Scalable Techniques, Dakshinamurthy Sharma Nagalingam

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Carbon foam has many applications in the fields of thermal management, net-shape composites and electronic cooling due to its porous structure, low density, electrical and thermal conductivities. However it is prone to oxidation at high temperatures in air. Whereas some previous studies have reported oxidation protective coatings on other carbon structures such as graphite parts and fibers, there is very limited work on foam. Moreover, earlier methods have used vapor phase techniques such as Plasma Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD). There is no known study involving such coatings using simple scalable liquid phase method. This thesis reports …

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Minute Doping Of Pulsed Laser Deposition Processed Y123 Thin Films With Tb, Ce, And Pr, Joseph William Kell Jan 2007

Minute Doping Of Pulsed Laser Deposition Processed Y123 Thin Films With Tb, Ce, And Pr, Joseph William Kell

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Three rare earth elements (Tb, Ce, and Pr) were chosen for the investigation into whether adding minute quantities (≤1 at%) of dopants could improve the film quality of YBa2C 3O7-δ(Y123) thin films. The compositions studied are (Y1-x,Rex)Ba2Cu3O7-δ (RE=Tb, Ce, Pr; x=0.1, 0.01, 0.001). Good quality thin films were produced by PLD and showed significant improvement to properties when exposed to a magnetic field. Ce and Pr (x=0.001) doped films showed modest improvement. However, the Tb doped system showed substantial improvement to Jc(H), with a …

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Low Voltage And Fast Speed All-Polymeric Optocouplers, Yan Yao, Hsiang-Yu Chen, Jinsong Huang, Yang Yang Jan 2007

Low Voltage And Fast Speed All-Polymeric Optocouplers, Yan Yao, Hsiang-Yu Chen, Jinsong Huang, Yang Yang

Department of Mechanical and Materials Engineering: Faculty Publications

An all-polymeric optocoupler has been demonstrated with a polymer light-emitting diode (PLED) as the light source (input unit) and a polymer/fullerene photodiode (PD) as the detector (output unit). The electroluminescence (EL) peak of the PLED is 560 nm, and the entire EL spectrum is within the response range of the PD. The optocoupler can work at low driving voltages, 5 V on the PLED and 0 V on the PD. The output photocurrent increases linearly with input current, and the current density transfer ratio reaches 1.5%. The frequency response of the optocoupler is at 500 kHz. With comparable performance to …

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Origin Of Photomultiplication In C60 Based Devices, Jinsong Huang, Yang Yang Jan 2007

Origin Of Photomultiplication In C60 Based Devices, Jinsong Huang, Yang Yang

Department of Mechanical and Materials Engineering: Faculty Publications

In this manuscript, the origin of the photomultiplication effect was studied in C60 based devices by evaluating the wavelength dependent external and internal quantum efficiencies under various biases. The effect of materials with disordered structures on the photomultiplication effect was determined by intentionally integrating both ordered and disordered material structures into one organic solar cell device with a configuration of indium tin oxide/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS)/pentacene/C60 fullerene/bathocuproine (BCP)/Al. Our results show that both the disordered structure of C60 and the charge trapping effect at the C60 /PEDOT:PSS interface contribute to the photomultiplication effect. By studying the C60-only …

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Deck-Mounted Steel Post Barrier System, John D. Reid, Ronald K. Faller, Jason A. Hascall Jan 2007

Deck-Mounted Steel Post Barrier System, John D. Reid, Ronald K. Faller, Jason A. Hascall

Department of Mechanical and Materials Engineering: Faculty Publications

An existing mountable safety barrier system, previously crash tested successfully on a wood bridge deck, was evaluated for use on a fiber reinforced plastic (FRP) bridge deck. In an attempt to avoid expensive full-scale crash testing, components of the existing system were evaluated using worst case conditions on two dynamic bogie crash tests and a series of computer simulations using nonlinear finite-element analysis. Simulation results closely approximated the physical results, with both displaying similar deformation, damage, and force levels. Both testing and simulation demonstrated that the barrier should function sufficiently if used on the FRP deck system. Further, the development …

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Regional Mechanical Properties And Stress Analysis Of The Human Anterior Lens Capsule, Ryan M. Pedrigi, G. David, J. Dziezyc, J. D. Humphrey Jan 2007

Regional Mechanical Properties And Stress Analysis Of The Human Anterior Lens Capsule, Ryan M. Pedrigi, G. David, J. Dziezyc, J. D. Humphrey

Department of Mechanical and Materials Engineering: Faculty Publications

The lens capsule of the eye functions, in part, as a deformable support through which the ciliary body applies tractions that can alter lens curvature and corresponding refractive power during the process of accommodation. Although it has long been recognized that characterization of the mechanical properties of the lens capsule is fundamental to understanding this physiologic process as well as clinical interventions, prior data have been limited by one-dimensional testing of excised specimens despite the existence of multiaxial loading in vivo. In this paper, we employ a novel experimental approach to study in situ the regional, multiaxial mechanical behavior of …

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A Scientific Foundation Of Collaborative Engineering, S. C.-Y. Lu, W. Elmaraghy, G. Schuh, R. Wilhelm Jan 2007

A Scientific Foundation Of Collaborative Engineering, S. C.-Y. Lu, W. Elmaraghy, G. Schuh, R. Wilhelm

Department of Mechanical and Materials Engineering: Faculty Publications

Collaborative engineering is the practical application of collaboration sciences to the engineering domain. In today’s highly connected technology-driven economy, the production industry must rely on the best practices of collaborative engineering to stay competitive when designing, manufacturing, and operating complex machines, processes, and systems on a global scale. Despite its importance, collaborative engineering is currently more of a practiced art than a scientific discipline. A better understanding of how engineers should collaborate with all stakeholders to accomplish complex tasks that fulfill our increasing social responsibilities is a grand challenge. However, because we currently lack well-defined sciences of human collaboration, we …

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Factors That Influence Visual Attention And Their Effects On Safety In Driving: An Eye Movement Tracking Approach, Larry Bargola Nabatilan Jan 2007

Factors That Influence Visual Attention And Their Effects On Safety In Driving: An Eye Movement Tracking Approach, Larry Bargola Nabatilan

LSU Doctoral Dissertations

Statistics show that a high percentage of road related accidents are due to factors that cause impaired driving. Since information extraction in driving is predominantly a visual task, visual distraction and its implications are therefore important safety issues. The main objective of this research is to study some of the implications of demands to human’s attention and perception and how it affects performance of tasks such as driving. Specifically, the study aims to determine the changes that occur in the visual behavior of drivers with different levels of driving experience by tracking the movement of the eye; examine the effects …

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Engineering A Photo-Control Mechanism For Rna Interference, Richard Andrew Blidner Jan 2007

Engineering A Photo-Control Mechanism For Rna Interference, Richard Andrew Blidner

LSU Doctoral Dissertations

RNA interference (RNAi) is a phenomenon in which RNA molecules elicit potent and sequence-specific post-transcriptional gene silencing. Nucleic acid chemical modifications have been incorporated to improve their pharmacological properties. Despite numerous developments in chemical modifications for increased stability, safety, and efficiency of these therapeutic agents, they still face challenges of spatial and temporal targeting. One potential targeting strategy uses photocaging techniques, which involves the covalent attachment of photolabile compounds to the effector NA species that blocks bioactivity until exposed to near UV-light. This work demonstrates that fully-2’-fluorinated nucleic acids (FNAs) can elicit RNAi and that these effectors are resistant to …

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Electrodeposition Of Multilayered Nanostructures For Giant Magnetoresistance And Thermoelectric Applications, Despina Davis Jan 2007

Electrodeposition Of Multilayered Nanostructures For Giant Magnetoresistance And Thermoelectric Applications, Despina Davis

LSU Doctoral Dissertations

The electrodeposition of novel materials such as multilayer nanotubes for giant magneto resistance (GMR) applications and bismuth telluride nanotubes for thermoelectric applications are presented in this dissertation. The motivation for the multilayer electrodeposition is the investigation of giant magnetoresistance (GMR), a change in the material resistance in an applied magnetic field as a consequence of antiferromagnetic coupling. The nanowire high aspect ratio geometry allows the measurement of GMR with the current applied perpendicular to the plane (CPP) of the multilayers, which has been theoretically identified as being larger than the GMR in the (CIP) configuration (current in plane of multilayers). …

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Aconitic Acid From Sugarcane: Production And Industrial Application, Nicolas Javier Gil Zapata Jan 2007

Aconitic Acid From Sugarcane: Production And Industrial Application, Nicolas Javier Gil Zapata

LSU Doctoral Dissertations

Trans aconitic acid (TAA) is the predominant organic acid in cane leaf matter (CLM) juice. Its concentration is three to six times higher than the level found in sugarcane stalks. The variation of composition in terms of total fermentable sugars (TFS), anions, and cations of the LCP85-384 sugarcane variety during 2003-2006 seasons, as well as the ripener (Polado-L®) effect were analyzed. TAA content ranged between 2.1-3.1 kg / t CLM. The TFS in CLM juice yielded a fermentation efficiency of 92%, four points lower than with sugar molasses. Liquid-liquid extraction (LLE), solid-liquid extraction and ion exchange were evaluated for the …

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