Radiochemistry Commons^™

Investigation Of The Structure And Dynamics Of Regioisomeric Eu³⁺ And Gd³⁺ Chelates Of Nb-Dotma: Implications For Mri Contrast Agent Design, Benjamin Charles Webber

Dissertations and Theses

The detection of disease and abnormal pathology by magnetic resonance imaging (MRI) has been aided significantly by the use of gadolinium (Gd³⁺)-based contrast agents (CAs) over the past three decades. MRI and MRI CAs play a critical role in diagnosing tumors and diseases of the central nervous system. The agents used clinically have been shown to safely increase MRI contrast despite the toxicity of Gd³⁺, owing to the high kinetic and thermodynamic stability of these chelates. However, current CAs enhance contrast at a small fraction of what is theoretically possible. This leads to the necessity of …

Investigation Of Storage-Phosphor Autoradiography For The Rapid Quantitative Screening Of Air Filters For Emergency Response Purposes, Athena Marie Gallardo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Past nuclear accidents, such as Chernobyl, resulted in a large release of radionuclides into the atmosphere. Radiological assessment of the vicinity of the site of the incident is vital to assess the exposure levels and dose received by the population and workers. Therefore, it is critical to thoroughly understand the situation and risks associated with a particular event in a timely manner in order to properly manage the event. Current atmospheric radiological assessments of alpha emitting radioisotopes include acquiring large quantities of air samples, chemical separation of radionuclides, sample mounting, counting through alpha spectrometry, and analysis of the data. The …

A, Catalysis Of Co-Prox By Water-Soluble Rhodium Fluorinated Porphyrins. B, Studies Toward Fluorination Of Electron Rich Aromatics By Nucleophilic Fluoride, Shri Harsha Uppaluri

Department of Chemistry: Dissertations, Theses, and Student Research

The rhodium(III) derivative of a water soluble, heavily fluorinated porphyrin is shown to catalyze the low temperature, low pressure selective oxidation of carbon monoxide in hydrogen gas streams for use in fuel cell applications. The catalytic activity is a direct result of the removal of electron density from the metal center. Selectivity for CO oxidation is a direct consequence of fluorination of the porphyrin periphery, since these substituents enhance the rate of the reaction and prevent the formation of Rh(II)-Rh(II) dimmers. Significantly, the dramatic increase in rhodium hydride acidity caused by fluorination precludes hydrogen activation and generation, thereby permitting preferential …

Separation Of Tc From U And Development Of Metallic Tc Waste Forms, Edward Mausolf

UNLV Theses, Dissertations, Professional Papers, and Capstones

The isotope Technetium-99 (⁹⁹Tc) is a major fission product of the nuclear industry. In the last decade, approximately 20 tons of 99Tc have been produced by the US nuclear industry. Due to its long half-life (t_1/2 = 214,000 yr), beta radiotoxicity, and high mobility as pertechnetate [TcO₄]^-, Tc represents long-term concern to the biosphere. Various options have been considered to manage ⁹⁹Tc. One of them is its separation from spent fuel, conversion to the metal and incorporation into a metallic waste form for long-term disposal. After dissolution of spent fuel in nitric …

Forensic Signatures Of Chemical Process History In Uranium Oxides, Jonathan Plaue

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation comprehensively explores and develops new tools for nuclear forensic science to facilitate the identification of chemical process history in uranium oxides. Nuclear forensics is an emerging discipline motivated by the need to prevent and combat malevolent acts involving nuclear and radiological materials. This dissertation examined process signatures in uranium oxide powders, precursors, and sintered fuel pellets.

Signatures were investigated on set of powder and pellet exemplars synthesized in the laboratory and a set of real‐world samples with process information obtained from the literature or manufacturer. The examined techniques included morphology as revealed by scanning electron microscopy, near‐infrared reflectance …

Density Functional Theory And The Calculation Of Tcmg2O4 Spinel Lattice Parameters, Jon Karlo Macias

Physics

The cohesive energy, lattice constant and bulk modulus of two simple HCP crystal structures of magnesium and technetium were calculated using the vienna ab initio simulation package (VASP) which is based on density functional theory (DFT). The same properties were determined for TcMg₂O₄ spinel. The theoretical results of the lattice constant of the pure crystals were compared to experimental results and found to be in excellent agreement with a difference of less than 2%. The results for the lattice constant of the TcMg₂O₄ spinel were found to be in excellent agreement as well with …

Synthesis: What We Have Learned From The East Texas Radiocarbon Database, Robert Z. Selden Jr., Timothy K. Perttula

CRHR: Archaeology

This poster provides a short overview of what we have learned from the East Texas Radiocarbon Database since it became available on the Council of Texas Archeologists’ website in 2011. These successes are numerous and include the advancement of novel methodological approaches; an improvement in our comprehension of the temporal nuances within the East Texas Archaic; the division of the East Texas Woodland period into Early, Middle and Late; the refinement of Caddo temporal chronology – particularly from a geographic perspective -- and it has provided one line of evidence to use to argue for the fluorescence of corn-based agriculture …

A Preliminary Temporal Analysis Of The East Texas Archaic, Robert Z. Selden Jr.

CRHR: Archaeology

This article presents preliminary findings of a temporal analysis of the East Texas Archaic based upon the examination of radiocarbon dates that have deposits that date to the period. All assays employed in this effort were collected from research and cultural resource management reports and publications, synthesized, then recalibrated in version 4.1.7 of OxCal.

Additional New Radiocarbon Dates From East Texas Caddo Sites, Timothy K. Perttula, Robert Z. Selden Jr.

CRHR: Archaeology

As a follow-up to the radiocarbon analyses reported by Perttula and Selden (2013), in this article, we report on five new radiocarbon dates obtained from Caddo sites in East Texas. The radiocarbon samples are charred organic remains scraped off of one surface of whole vessels or sherds. These samples are from the Ware Acres site (41GG31), the H. C. Slider site in Cherokee County, an unknown site in the upper Neches River basin in Smith County (9-SC), and an unknown Titus phase site (11-BCJ) in the Big Cypress Creek basin. All of the dates are calibrated using OxCal v4.1.7.

Temporal Dynamics Of East Texas Caddo Sites With 10 Or More Radiocarbon Dates, Robert Z. Selden Jr., Timothy K. Perttula

CRHR: Archaeology

This article represents supplementary data (see Selden and Perttula 2013) highlighting the specifics of date combination and the subsequent production of summed probability distribution samples for Caddo sites in East Texas. All radiocarbon (14C ) dates employed in this effort were collected from research and cultural resource management (CRM) reports and publications, synthesized, then recalibrated in version 4.1.7 of OxCal (Bronk Ramsey 2012) using IntCal09 (Reimer et al. 2009) (Perttula and Selden 2011).

New Radiocarbon Dates From East Texas Caddo Sites, Timothy K. Perttula, Robert Z. Selden Jr.

CRHR: Archaeology

In this article, we report on new radiocarbon dates obtained from five Caddo sites in East Texas. The radiocarbon samples are charred organic remains scraped off of one surface of whole vessels or sherds. These samples are from the Johns (41CP12), Shelby Mound (41CP71), Gilbert (41RA13), Henry Spencer (41UR315), and Henry Williams (41UR318) sites. All of the dates are calibrated using OxCal v4.1.7 (Bronk Ramsey 2012), with atmospheric data from Reimer et al. (2009).