Physics Commons^™

Impact Of The Synthesis Process On Structure Properties For Afci Fuel Candidates, Kenneth Czerwinski

Fuels Campaign (TRP)

Synthesis of actinium mononitrides using carbothermic reduction of the corresponding oxides has a few outstanding issues, including the formation of secondary phases such as oxides and carbides and low densities of the final product. Furthermore the requirement of a high process temperature at 1700°C, for more than 12 hours is also a drawback particularly for Americium-bearing samples. Therefore, it is important to explore the use of other possible routes to synthesize actinide mononitrides.

A low temperature process is used in this research to produce actinide mononitrides using a fluoride route in which the first step is to mix the actinide …

Solution-Based Synthesis Of Nitride Fuels, Tyler A. Sullens, Kenneth Czerwinski

Fuels Campaign (TRP)

The preliminary studies into the synthesis of actinide nitride fuels through a low temperature, liquid ammonia based synthesis route have been conducted on the uranium containing system, and there is good indication for the success of synthesizing uranium (III) nitride. The dissolution of iodine in ammonia is a rapid process, resulting in a pale green solution, which does not result in any observable oxidation of iodine. The cannula transfer of dissolved iodine into the reaction vessel containing U metal has been conducted with little to no residual iodine remaining in the original flask. The metal being used for these reactions …

Colour Doppler Spatial Resolution Performance Testing, Jacinta Browne, Ian Brown, Peter Hoskins, Amanda Watson, Alex Elliott

Articles

No abstract available

Searches For Periodic Gravitational Waves From Unknown Isolated Sources And Scorpius X-1: Results From The Second Ligo Science Run, B. P. Abbott, R. Abbott, Mario C. Diaz, R. Grosso, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres

Physics & Astronomy Faculty Publications

We carry out two searches for periodic gravitational waves using the most sensitive few hours of data from the second LIGO science run. Both searches exploit fully coherent matched filtering and cover wide areas of parameter space, an innovation over previous analyses which requires considerable algorithm development and computational power. The first search is targeted at isolated, previously unknown neutron stars, covers the entire sky in the frequency band 160–728.8 Hz, and assumes a frequency derivative of less than 4×10−10  Hz/s. The second search targets the accreting neutron star in the low-mass x-ray binary Scorpius X-1 and covers the frequency …

Hologram-Based Humidity Indicator For Domestic And Packaging Applications, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin

Conference Papers

A passive indicator for Relative Humidity based on a photopolymer recorded hologram has been developed. The indicator works on the principle that the wavelength reconstructed by a reflection hologram is dependent on the spacing between the fringe planes of the hologram. As the Relative Humidity changes, the hologram swells or shrinks and the apparent colour of the reconstructed image changes. The response time, operational range and reversibility of the indicator have been studied in a controlled humidity environment. Response times from less than a minute to tens of minutes depending on the holograms physical properties have been measured. Indicators with …

Two-Dimensional Guided Mode Resonant Structures For Spectral Filtering Applications, Sakoolkan Boonruang

Electronic Theses and Dissertations

Guided mode resonant (GMR) structures are optical devices that consist of a planar waveguide with a periodic structure either imbedded in or on the surface of the structure. The resonance anomaly in GMR structures has many applications as dielectric mirrors, tunable devices, sensors,and narrow spectral band reflection filters. A desirable response from a resonant grating filter normally includes a nearly 100% narrowband resonant spectral reflection (transmission), and a broad angular acceptance at either normal incidence or an oblique angle of incidence. This dissertation is a detailed study of the unique nature of the resonance anomaly in GMR structures with two-dimensional …

Raman Spectroscopic Study Of Single Red Blood Cells Infected By The Malaria Parasite Plasmodium Falciparum, William Carter

Electronic Theses and Dissertations

Raman micro-spectroscopy provides a non-destructive probe with potential applications as a diagnostic tool for cellular disorders. This study presents micro-Raman spectra of live erythrocytes infected with a malaria parasite and investigates the potential of this probe to monitor molecular changes which occur during differentiation of the parasite inside the cell. At an excitation wavelength of 633 nm the spectral bands are dominated by hemoglobin vibrations yielding information the on structure and spin state of the heme moiety. It also demonstrates the novel use of silica capillaries as a viable method for studying the erythrocytes in an environment that is much …

Scanning Fabry-Perot Spectrometer For Terahertz And Gigahertz Spectroscopy Using Dielectric Bragg Mirrors, Justin Cleary

Electronic Theses and Dissertations

A scanning Fabry-Perot transmission filter composed of a pair of dielectric mirrors has been demonstrated at millimeter and sub-millimeter wavelengths. The mirrors are formed by alternating quarter-wave optical thicknesses of silicon and air in the usual Bragg configuration. Detailed theoretical considerations are presented for determining the optimum design including factors that affect achievable finesse. Fundamental loss by lattice and free carrier absorption are considered. High resistivity in the silicon layers was found important for achieving high transmittance and finesse, especially at the longer wavelengths. Also considered are technological factors such as surface roughness, bowing, and misalignment for various proposed manufacturing …

Frequency Distribution Of Pyroxene Types And A Method To Separate The Composition Of Multiple Pyroxenes In A Sample, Jimmy Allen Davis

Electronic Theses and Dissertations

Determining mafic mineral composition of asteroid bodies is a topic reviewed by M.J. Gaffey et al. (2002). The iterative procedure discussed can be implemented as an algorithm, and such efforts revealed weaknesses that are examined in this work. We seek to illustrate the limits of this method and graphically determine its predictions. There are boundaries in the formulae given where the equations break down. In ranges where mafic mixtures are predicted, a method is illustrated that allows a decoupling of these mixtures into the constituents.

Spectroscopic Studies Of Laser Plasmas For Euv Sources, Simi A. George

Electronic Theses and Dissertations

With the availability of high reflectivity multilayer mirrors and zone plate lenses, the EUV region (5nm - 40nm) of the electromagnetic spectrum is currently being explored for applications of nanoscale printing and imaging. Advances made in this area have consequences for many areas of science. Research for producing a compact, bright EUV source for laboratory use has gained momentum in recent years. For this study, EUV radiation is produced by irradiating target materials using a focused laser beam. Focused laser beam ionizes the target to create a hot, dense, pulsed plasma source, where emission is a result of the relaxation …

Modeled And Observed N2 Lyman-Birge-Hopfield Band Emissions Earth's Dayglow: A Comparison, Donald Murray

Electronic Theses and Dissertations

Ultraviolet (UV) spectra obtained from Earth’s dayglow contain important information for understanding the thermosphere, and the N2 Lyman-Birge-Hopfield (LBH) bands are possibly the most useful emission. To be useful, a thorough understanding of how the LBH band emission varies with altitude and latitude is essential to present and future use of this emission by space-based remote sensors. Excited by photoelectron impact on N2 leading to transitions from the a 1Πg state to the ground state, the LBH emissions radiate between 1270 and 2400 Å. In addition to being populated by electron impact excitation, the a 1Πg state is populated by …

High Birefringence Liquid Crystals For Optical Communications, Amanda Jane Parish

Electronic Theses and Dissertations

High birefringence (Δn > 0.4) nematic liquid crystals are particularly attractive for infrared applications because they enable a thinner cell gap to be used for achieving fast response time and improved diffraction efficiency. In this thesis, the mesomorphic and electro‐optic properties of several new fluorinated isothiocyanate (NCS) terphenyl and phenyl tolane single compounds and mixtures are reported. The single compounds demonstrated Δn~0.35‐0.52 in the visible spectral region at room temperature and exhibit relatively low viscosity. It was found that lateral fluorine substitutions and short alkyl chains eliminate smectic phase and lower the melting temperature of the single compounds. However, the consequence …

Surface Characterization Of Thin Film Zno Capacitors By Capacitance-Voltage Measurements, Linda Smith

Electronic Theses and Dissertations

The main objective of the research was the fabrication and characterization of MOS/MIS capacitors with ZnO as the insulating layer. Comparison with the already well known behavior of MOS/MIS capacitors with SiO2 as insulator was used to facilitate determination of the ZnO characteristics. Moreover, thermal annealing of the samples led to increased understanding of the role of defects on the dielectric properties of the ZnO layers in the MOS/MIS devices. Hall-effect transport measurements and x-ray diffraction (XRD) spectroscopy are used to analyze the structure and electronic surface characteristics of the ZnO insulator. Capacitance-voltage (C-V) measurements are used to understand the …

Discrete Surface Solitons, Sergiy Suntsov

Electronic Theses and Dissertations

Surface waves exist along the interfaces between two different media and are known to display properties that have no analogue in continuous systems. In years past, they have been the subject of many studies in a diverse collection of scientific disciplines. In optics, one of the mechanisms through which optical surface waves can exist is material nonlinearity. Until recently, most of the activity in this area was focused on interfaces between continuous media but no successful experiments have been reported. However, the growing interest that nonlinear discrete optics has attracted in the last two decades has raised the question of …

Design And Demonstration Of Meanderline Retarders At Infrared Frequencies, Jeffrey Scott Tharp

Electronic Theses and Dissertations

Meanderline structures are widely used as engineered birefringent materials for waveplates and retarders at radiofrequencies, and have been previously demonstrated at frequencies up to 90 GHz in the millimeter-wave band. In this dissertation, we present results related to the modeling, fabrication, and experimental characterization of meanderlines across the range from 30 to 100 THz, in the long-wave and mid-wave infrared bands. Specific issues addressed in these new designs include spectral dispersion and angular dependence of the retardance, as well as axial ratio and throughput. The impact resulting from the infrared properties of the metals and dielectrics is explicitly included throughout. …

Influence Of Electron Trapping On Minority Carrier Transport Properties Of Wide Band Gap Semiconductors, Olena Tirpak

Electronic Theses and Dissertations

Minority carrier transport properties and the effects of electron irradiation/injection were studied in GaN and ZnO containing dopants known to form acceptor states deep within the materials' bandgap. Minority carrier diffusion length and lifetime changes were investigated using Electron Beam Induced Current (EBIC) method, cathodoluminescence spectroscopy, spectral photoresponse and persistent photoconductivity measurements. It is shown that electron irradiation by the beam of a scanning electron microscope results in a significant increase of minority carrier diffusion length. These findings are supported by the cathodoluminescence measurements that demonstrate the decay of near-band-edge intensity as a consequence of increasing carrier lifetime under continuous …

Model Studies Of Time-Dependent Ducting For High-Frequency Gravity Waves And Associated Airglow Responses In The Upper Atmospher, Yonghui Yu

Electronic Theses and Dissertations

This doctoral dissertation has mainly concentrated on modeling studies of shorter period acoustic-gravity waves propagating in the upper atmosphere. Several cases have been investigated in the literature, which are focusing on the propagation characteristics of high-frequency gravity wave packets. The dissertation consists of five main divisions of which each has its own significance to be addressed, and these five chapters are also bridged in order with each other to present a theme about gravity wave ducting dynamics, energetics, and airglows. The first chapter is served as an introduction of the general topic about atmospheric acoustic-gravity waves. Some of the historical …

Generalized No-Broadcasting Theorem, Howard Barnum, Jonathan Barrett, Matthew S. Leifer, Alex Wilce

Mathematics, Physics, and Computer Science Faculty Articles and Research

We prove a generalized version of the no-broadcasting theorem, applicable to essentially any nonclassical finite-dimensional probabilistic model satisfying a no-signaling criterion, including ones with ‘‘superquantum’’ correlations. A strengthened version of the quantum no-broadcasting theorem follows, and its proof is significantly simpler than existing proofs of the no-broadcasting theorem.

Low And Medium Β Superconducting Cavities And Accelerators, Jean R. Delayen

Physics Faculty Publications

No abstract provided.

An Evaluation Of Supercritical Drying And Peg/Freeze Drying Of Waterlogged Archaeological Wood, Eric Schindelholz, Robert Blanchette, Desmond C. Cook, Michael Drews, Steve Hand, Benjamin Held, Joel Jurgens, Betty Seifert

Physics Faculty Publications

This study was undertaken to evaluate the physical effects of drying waterlogged archaeological wood using supercritical carbon dioxide as compared to air drying and the popular polyethylene glycol (PEG)/freeze drying method. Previous studies have shown supercritical drying to be a potentially advantageous alternative to current methods of drying waterlogged wood through reduced processing time, minimal shrinkage, and increased success for reversibility. Samples in the form of blocks and planks of a few centimeters in size were prepared from two archaeological waterlogged wood sources and grouped into three treatment sets: one for air drying, one for PEG/freeze drying, and the other …

A New Approach To The Toxicity Testing Of Carbon-Based Nanomaterials: The Clonogenic Assay, Eva Herzog, Alan Casey, Fiona Lyng, Gordon Chambers, Hugh Byrne, Maria Davoren

Articles

The cellular toxicity of three types of carbon nanoparticles, namely HiPco® single-walled carbon nanotubes (SWCNT), arc dischargeSWCNTand Printex 90 carbon black nanoparticles,was studied on three different cell models including the human alveolar carcinoma epithelial cell line (A549), the normal human bronchial epithelial cell line (BEAS-2B) and the human keratinocyte cell line (HaCaT) using the clonogenic assay. Carbon nanomaterials are known to interact with colorimetric indicator dyes frequently used in cytotoxicity assays. By employing the clonogenic assay, any such interactions could be avoided, allowing a more reliable method for the in vitro toxicity assessment of carbon-based nanoparticles. It could be shown …

Search For Stop Production In R-Parity-Violating Supersymmetry At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, L. Rinaldi, G. Sartorelli

Faculty Publications

A search for stop production in R-parity-violating supersymmetry has been performed in e+p interactions with the ZEUS detector at HERA, using an integrated luminosity of 65 pb-1. At HERA, the R-parity-violating coupling λ' allows resonant squark production, e+d→̃ q. Since the lowest-mass squark state in most supersymmetry models is the light stop, ̃t, this search concentrated on production of ̃t, followed either by a direct R-parity-violating decay, or by the gauge decay to b̃x1+. No evidence for stop production was found and limits were set on λ'131 as a function of the stop mass in the framework of the minimal …

Sound Spectral Analysis Of Uni Carillon Bells, Kimberly Cordray

Honors Program Theses

The campanile located in the center of the University of Northern Iowa campus has been a symbol of the university since its completion in 1926. This 100 foot tall structure was the chosen memorial celebrating the 50th anniversary of the university and dedicated to the founders and builders. But this towering structure is more than just a popular gathering point and icon, it houses 4 7 bells and a carillon instrument which plays these bells.

Bells are a unique and complex instrument. It is not hard to comprehend when you think about what a bell is. A carillon bell is …

Magneto-Aerotaxis, Richard B. Frankel, Timothy J. Williams, Dennis A. Bazylinski

Physics

Magnetotactic bacteria orient and migrate along geomagnetic field lines. Magneto-aerotaxis increases the efficiency of respiring cells to efficiently find and maintain position at a preferred microaerobic oxygen concentration. Magneto-aerotaxis could also facilitate access to regions of higher nutrient and electron acceptor concentration via periodic excursions above and below the preferred oxygen concentration level.

Development Of A High Performance Parallel Computing Platform And Its Use In The Study Of Nanostructures : Clusters, Sheets And Tubes ., S. Gowtham

Dissertations, Master's Theses and Master's Reports - Open

Small clusters of gallium oxide, technologically important high temperature ceramic, together with interaction of nucleic acid bases with graphene and small-diameter carbon nanotube are focus of first principles calculations in this work. A high performance parallel computing platform is also developed to perform these calculations at Michigan Tech. First principles calculations are based on density functional theory employing either local density or gradient-corrected approximation together with plane wave and gaussian basis sets.

The bulk Ga₂O₃ is known to be a very good candidate for fabricating electronic devices that operate at high temperatures. To explore the properties of …

First-Principles Studies Of Boron Nanostructures, Kah Chun Lau

Dissertations, Master's Theses and Master's Reports - Open

Boron is an 'electron deficient' element which has a rather fascinating chemical versatility. In the solid state, the elemental boron has neither a pure covalent nor a pure metallic character. As a result, its vast structural dimensionally and peculiar bonding features hold a unique place among other elements in the periodic table. In order to understand and properly describe these unusual bonding features, a detailed and systematic theoretical study is needed. In this work, I will show that some of the qualitative features of boron nanostructures, including clusters, sheets and nanotubes can easily be extracted from the results of first …