Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Atomic, Molecular and Optical Physics

University of Nevada, Las Vegas

Articles 1 - 9 of 9

Full-Text Articles in Engineering

Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger Dec 2018

Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger

UNLV Theses, Dissertations, Professional Papers, and Capstones

X-ray induced damage is generally considered a nuisance, but in the field of Useful Hard X-ray Photochemistry we harness the highly ionizing and penetrating properties of hard X-rays (> 7 keV) to initiate novel photochemical decomposition and synthesis at ambient and extreme conditions. Preliminary experiments suggest that the energy of irradiating photons and the sample pressure play roles in determining the nature of X-ray induced damage. Here, we present the X-ray energy dependence of damage induced in strontium oxalate, strontium nitrate, and barium nitrate, as well as the pressure dependence of X-ray induced damage of strontium oxalate. Our results indicate …


Transparent Actuator Made With Few Layer Graphene Electrode And Dielectric Elastomer, For Variable Focus Lens, Taeseon Hwang, Hyeok-Yong Kwon, Joon-Suk Oh, Jung-Pyo Hong, Seung-Chul Hong, Youngkwan Lee, Hyouk Ryeo Choi, Kwang J. Kim, Mainul Hossain Bhuiya, Jae Do Nam Jan 2013

Transparent Actuator Made With Few Layer Graphene Electrode And Dielectric Elastomer, For Variable Focus Lens, Taeseon Hwang, Hyeok-Yong Kwon, Joon-Suk Oh, Jung-Pyo Hong, Seung-Chul Hong, Youngkwan Lee, Hyouk Ryeo Choi, Kwang J. Kim, Mainul Hossain Bhuiya, Jae Do Nam

Mechanical Engineering Faculty Research

A transparent dielectric elastomer actuator driven by few-layer-graphene (FLG) electrode was experimentally investigated. The electrodes were made of graphene, which was dispersed inN-methyl-pyrrolidone. The transparent actuator was fabricated from developed FLG electrodes.The FLG electrode with its sheet resistance of 0.45 kΩ/sq (80 nm thick) was implemented to mask silicone elastomer. The developed FLG-driven actuator exhibited an optical transparency of over 57% at a wavenumber of 600 nm and produced bending displacement performance ranging from 29 to 946 μm as functions of frequency and voltage. The focus variation was clearly demonstrated under actuation to study its application-feasibility in …


Hybrid Plasmonic Nanoantennas: Fabrication, Characterization, And Application, Shengjie Zhai Dec 2012

Hybrid Plasmonic Nanoantennas: Fabrication, Characterization, And Application, Shengjie Zhai

UNLV Theses, Dissertations, Professional Papers, and Capstones

As optical counterpart of microwave antennas, plasmonic nanoantennas are important nanoscale devices for converting propagating optical radiation into confined/enhanced electromagnetic fields. Presently, nanoantennas, with a typical size of 200-500 nm, have found their applications in bio-sensing, bio-imaging, energy harvesting, and disease cure and prevention. With the device feature size of next generation IC goes down to 22 nm or smaller, and biological/chemical sensing reaches the Gene’s level, the sizes of the corresponding nanoantennas have to be scaled down to sub-100nm level. In the literature, these sub-100nm nanoantennas are referred as deep subwavelength nanoantennas as size of such miniaturized nanoantennas is …


Structure Studies On Lanthanide Technetium Pyrochlores As Prospective Host Phases To Immobilize 99- Technetium And Fission Lanthanides From Effluents Of Reprocessed Used Nuclear Fuels, Thomas Hartmann, Ariana Alaniz Apr 2011

Structure Studies On Lanthanide Technetium Pyrochlores As Prospective Host Phases To Immobilize 99- Technetium And Fission Lanthanides From Effluents Of Reprocessed Used Nuclear Fuels, Thomas Hartmann, Ariana Alaniz

Festival of Communities: UG Symposium (Posters)

We performed a systematic investigation of the incorporation of 99Tc into pyrochlore oxide structures, Ln2Tc2O7, where Ln represents trivalent lanthanide Ln3+ cations, while 99Tc is atetravalent, Tc4+, metal cation. Pyrochlore compounds are high-melting temperature oxides and are recognized for their durability. Our goal in this preliminary study is to characterize and quantify the range of stability of the lanthanum technetium pyrochlore oxide phase. Hereby, powder X-ray diffraction (XRD) and Rietveld analysis were used to determine and characterize the crystalline phase content with high accuracy, and scanning electron microscopy (SEM) was used to characterize the microstructure and homogeneity of the synthesized …


X-Ray Diffraction On The Thermoelectric Silicides At High Pressure, Deep Patel, Ravhi S. Kumar, Andrew Cornelius Apr 2011

X-Ray Diffraction On The Thermoelectric Silicides At High Pressure, Deep Patel, Ravhi S. Kumar, Andrew Cornelius

Festival of Communities: UG Symposium (Posters)

Cobalt Silicide (CoSi2) is a transition metal disilicide that has gathered scientific interest due to its interesting thermoelectric properties and applications in silicon-based devices because of their high temperature stability. It has been reported that CoSi2 undergoes a phase transition at around 0.4 GPa and again at 13 GPa. Furthermore, at 13 GPa the material changes from a cubic cell to an orthorhombic cell, but details of the phase transition at 0.4 GPa could not be determined. To further study the properties of CoSi2 and understand its pressure induced phase changes, we recorded the structural behavior of CoSi2 under pressure.


Investigation Of Structural And Magnetic Properties Of Iron Clusters Encapsulated In Carbon, Andrew Mohrland, Eunja Kim, Phillipe Weck, Pang Tao, Kenneth Czerwinski Apr 2011

Investigation Of Structural And Magnetic Properties Of Iron Clusters Encapsulated In Carbon, Andrew Mohrland, Eunja Kim, Phillipe Weck, Pang Tao, Kenneth Czerwinski

Festival of Communities: UG Symposium (Posters)

Our goal is to investigate and predict the properties of iron-carbon nanostructures by performing numerical calculations using the density-functional theory. We are interested in which nanostructures are most stable, and in how they are likely to form. We have a particular interest in the magnetic properties of carbon "buckyballs" containing iron particles. These structures have potential for biomedical application, including use in anti-cancer treatment. Lone iron clusters have potential for use as a catalyst designed to reduce vehicle emissions.


Pressure-Driven Transport Of Particles Through A Converging-Diverging Microchannel, Ye Ai, Sang W. Joo, Yingtao Jiang, Xiangchun Xuan, Shizhi Qian Jun 2009

Pressure-Driven Transport Of Particles Through A Converging-Diverging Microchannel, Ye Ai, Sang W. Joo, Yingtao Jiang, Xiangchun Xuan, Shizhi Qian

Mechanical Engineering Faculty Research

Pressure-driven transport of particles through a symmetric converging-diverging microchannel is studied by solving a coupled nonlinear system, which is composed of the Navier–Stokes and continuity equations using the arbitrary Lagrangian–Eulerian finite-element technique. The predicted particle translation is in good agreement with existing experimental observations. The effects of pressure gradient, particle size, channel geometry, and a particle’s initial location on the particle transport are investigated. The pressure gradient has no effect on the ratio of the translational velocity of particles through a converging-diverging channel to that in the upstream straight channel. Particles are generally accelerated in the converging region and then …


Yttrium And Hydrogen Superstructure And Correlation Of Lattice Expansion And Proton Conductivity In The Bazr0.9y0.1o2.95 Proton Conductor, A. Braun, A. Ovalle, V. Pomjakushin, A. Cervellino, S. Erat, Wayne C. Stolte, T. Graule Jan 2009

Yttrium And Hydrogen Superstructure And Correlation Of Lattice Expansion And Proton Conductivity In The Bazr0.9y0.1o2.95 Proton Conductor, A. Braun, A. Ovalle, V. Pomjakushin, A. Cervellino, S. Erat, Wayne C. Stolte, T. Graule

Chemistry and Biochemistry Faculty Research

Bragg reflections in Y-resonant x-ray diffractograms of BaZr0.9Y0.1O2.95 (BZY10) reveal that Y is organized in a superstructure. Comparison with neutron diffraction superstructure reflections in protonated/deuterated BZY10 suggests that both superstructures are linked, and that protons move in the landscape imposed by the Y. The thermal lattice expansion decreases abruptly for protonated BZY10 at T≥648±20 K, coinciding with the onset of lateral proton diffusion and suggesting a correlation of structural changes and proton conductivity. The chemical shift in the Y L1-shell x-ray absorption spectra reveals a reduction from Y3+ toward Y2+ upon …


Investigation Of The Corrosion Of Steel By Lead-Bismuth Eutectic (Lbe) Using Scanning Electron Microscopy And X-Ray Photoelectron Spectroscopy, Daniel Koury Dec 2002

Investigation Of The Corrosion Of Steel By Lead-Bismuth Eutectic (Lbe) Using Scanning Electron Microscopy And X-Ray Photoelectron Spectroscopy, Daniel Koury

UNLV Theses, Dissertations, Professional Papers, and Capstones

Lead Bismuth Eutectic (LBE) has been proposed for use in programs for accelerator transmutation of waste. LBE is the leading candidate material as a spallation target and an option for the sub-critical blanket coolant. The corrosion of 316 and 316L stainless steels by LBE has been studied using UNLV's facilities for Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). We have compared exposed and unexposed samples and studied the differences. Some amount of surface contamination is present on the samples and has been removed by ionbeam etching. The unexposed samples reveal typical stainless steel characteristics: a chromium oxide passivation …