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Articles 1 - 30 of 111
Full-Text Articles in Radiochemistry
Impact Of Collodion Thickness On Fission Track Generation Within Lexan Employed For Nuclear Forensic Analyses, Ryan K. Chapman, Zachary P. Meisel, Abigail A. Bickley
Impact Of Collodion Thickness On Fission Track Generation Within Lexan Employed For Nuclear Forensic Analyses, Ryan K. Chapman, Zachary P. Meisel, Abigail A. Bickley
Faculty Publications
We report results from a computational study of fission track damage within a Lexan substrate caused by 235U suspended within a collodion film of varied thickness. MCNP6.3 was used to model energy deposition and displacements per atom within a Lexan film coated by a film of collodion, located within the air-filled 6 inch dry tube of a TRIGA reactor. The collodion layer was varied between 20 and 100 μm thickness, resulting in an 8.8% difference in energy deposition and 12% difference in displacements-per-atom within the Lexan substrate. These findings indicate that collodion adhesive thickness has a moderate impact on …
Uranium Chemical Compound Classification Using Sub-Images And Statistical Machine Learning For Nuclear Forensics, Lee C. Lambert, Brett J. Borghetti, Abigail A. Bickley
Uranium Chemical Compound Classification Using Sub-Images And Statistical Machine Learning For Nuclear Forensics, Lee C. Lambert, Brett J. Borghetti, Abigail A. Bickley
Faculty Publications
Uranium particle analysis from Scanning Electron Microscope (SEM) imagery is a crucial tool in nuclear forensics. The particle morphology lexicon proposed by Tamasi et al. in J Radioanal Nucl Chem 307, 1611–1619 (2016) follows a standardized, manual identification process to identify particle morphology features. The present work seeks to mirror this methodology using computer feature selection from the scikit-image Python library rather than human classification. Using a random forest classifier, a 56% overall uranium true positive classification accuracy (a 39.6% balanced classification accuracy) was achieved on a test set outperforming a naïve (chance) model by 48%. The methodology introduced splits …
A Study On The Great Comet Of 2024: C/2023 A3 (Tsuchinshan–Atlas) Via Radio Interferometry, Jesse Bier, Nathan X. Roth
A Study On The Great Comet Of 2024: C/2023 A3 (Tsuchinshan–Atlas) Via Radio Interferometry, Jesse Bier, Nathan X. Roth
Undergraduate Research Symposium
Our solar system is approximately 4.5 billion years old. Comets are remnants of its formation, serving as time capsules to give us an understanding of its natal heritage. Revealing our own solar system’s history allows us to gain insights into other young stellar systems and the potential for life elsewhere. C/2023 A3 (Tsuchinshan–ATLAS) was a comet from the Oort cloud on its first and possibly only journey to the inner solar system. The comet grew in brightness until it was brighter than Venus on October 9th, 2024, making it temporarily brighter than Venus and one of the brightest …
Compton Scattering Of Mammographic Soft X-Ray Beams By Alkali And Transition Metal Salt Filters Produce X-Ray Interference Zones That May Have Treatment Potential For Localized Cancer Lesions, Subhendra N. Sarkar, Eric Lobel, Sabina Rakhmatova, Derbie Desir, Somdat Kissoon, Daler Djuraev, Katie Tam
Compton Scattering Of Mammographic Soft X-Ray Beams By Alkali And Transition Metal Salt Filters Produce X-Ray Interference Zones That May Have Treatment Potential For Localized Cancer Lesions, Subhendra N. Sarkar, Eric Lobel, Sabina Rakhmatova, Derbie Desir, Somdat Kissoon, Daler Djuraev, Katie Tam
Publications and Research
In breast x-ray imaging scattered radiation adds 50% of harmful radiation dose from anisotropic Compton scattering mechanism. We have been working with double layered inorganic salt materials that can induce Compton scattering to the incident mammographic x ray beams (in 20-30 kVp range) with adequate isotropy (angular control). Typically metal nitrates and alkali halide salt layers are shown here to cause low energy radiation interference zones with high and low photon intensities and local flux heterogeneity in terms of flux covariance. Spatial variation of low energy photon flux creates concentrated and sparse radiation zones that may be used to induce …
Synthesis Of Bis-Thioacid Derivatives Of Diarylethene And Their Photochromic Properties, Pramod Aryal, Jonathan Bietsch, Gowri Sankar Grandhi, Richard Chen, Surya B. Adhikari, Ephraiem S. Sarabamoun, Joshua J. Choi, Guijun Wang
Synthesis Of Bis-Thioacid Derivatives Of Diarylethene And Their Photochromic Properties, Pramod Aryal, Jonathan Bietsch, Gowri Sankar Grandhi, Richard Chen, Surya B. Adhikari, Ephraiem S. Sarabamoun, Joshua J. Choi, Guijun Wang
Chemistry & Biochemistry Faculty Publications
Diarylethenes (DAEs) are an important class of photoswitchable compounds that typically undergo reversible photochemical conversions between the open and closed cyclized forms upon treatment with UV light or visible light. In this study, we introduced thioacid functional groups to several photochromic dithienylethene (DTE) derivatives and established a method that can be used to prepare these photoswitchable thioacids. Four thioacid-functionalized diarylethene derivatives were synthesized through the activation of carboxylic acids with N-hydroxysuccinimide, followed by reactions with sodium hydrosulfide with yields over 90%. These derivatives exhibited reversible photoswitching and photochromic properties upon treatment with ultraviolet (UV) and visible lights. The thioacid groups …
The High Pressure Dependence Of X-Ray Induced Decomposition Of Cadmium Oxalate, Adrian F. Lua Sanchez, Petrika Cifligu, Marc Graff, Michael Pravica, Pradip K. Bhowmik, Changyong Park, Egor Evlyukhin
The High Pressure Dependence Of X-Ray Induced Decomposition Of Cadmium Oxalate, Adrian F. Lua Sanchez, Petrika Cifligu, Marc Graff, Michael Pravica, Pradip K. Bhowmik, Changyong Park, Egor Evlyukhin
Physics & Astronomy Faculty Research
The high proclivity of x rays to destabilize and distort molecular structures has been previously utilized in the synthesis of novel compounds. Here, we show that x-ray induced decomposition of cadmium oxalate induces chemical and structural transformations only at 0.5 and 1 GPa. Using x-ray diffraction and Raman spectroscopy, the synthesized product is identified as cadmium carbonate with cadmium oxalate remnants, which is stable under ambient conditions. At ambient and >1 GPa pressures, only degradation of the electronic density distribution is observed. The transformation kinetics are examined in terms of Avrami’s model, which demonstrates that despite the necessity of high …
Corrosion Related To The Nuclear Waste Containers, Ali Ebrahimzadeh Pilehrood
Corrosion Related To The Nuclear Waste Containers, Ali Ebrahimzadeh Pilehrood
Corrosion Research
The disposal of nuclear waste is a demanding topic, and the existing methods, whether it is temporary storage in spent fuel pools or storage in geological repositories, both face the risk of corrosion-related problems. Any failure in these storage methods can potentially lead to the release of radioactive materials into the environment. To avert such catastrophic scenarios, people in the nuclear industry consistently monitor and maintain these storage facilities endlessly and attempt to improve the plans designed to store nuclear waste. Here, I will examine the nuclear waste management organization (NWMO) plan in Canada. Choosing an appropriate location for the …
Techno-Economic Feasibility Analysis Of A Fully Mobile Radiation Oncology System Using Monte Carlo Simulation, Alex T. Price, Casey I. Canfield, Geoffrey D. Hugo, James A. Kavanaugh, Lauren E. Henke, Eric Laugeman, Pamela Samson, Clair Reynolds-Kueny, Elizabeth A. Cudney
Techno-Economic Feasibility Analysis Of A Fully Mobile Radiation Oncology System Using Monte Carlo Simulation, Alex T. Price, Casey I. Canfield, Geoffrey D. Hugo, James A. Kavanaugh, Lauren E. Henke, Eric Laugeman, Pamela Samson, Clair Reynolds-Kueny, Elizabeth A. Cudney
Engineering Management and Systems Engineering Faculty Research & Creative Works
PURPOSEDisparities in radiation oncology (RO) can be attributed to geographic location, socioeconomic status, race, sex, and other societal factors. One potential solution is to implement a fully mobile (FM) RO system to bring radiotherapy to rural areas and reduce barriers to access. We use Monte Carlo simulation to quantify techno-economic feasibility with uncertainty, using two rural Missouri scenarios.METHODSRecently, a semimobile RO system has been developed by building an o-ring linear accelerator (linac) into a mobile coach that is used for temporary care, months at a time. Transitioning to a more FM-RO system, which changes location within a given day, presents …
Growth Kinetics Determine The Polydispersity And Size Of Pbs And Pbse Nanocrystals, Michael P. Campos, Jonathan De Roo, Matthew W. Greenberg, Brandon M. Mcmurtry, Mark P. Hendricks, Ellie Bennett, Natalie Saenz, Matthew Y. Sfeir, Benjamin Abecassis, Sanjit K. Ghose, Jonathan S. Owen
Growth Kinetics Determine The Polydispersity And Size Of Pbs And Pbse Nanocrystals, Michael P. Campos, Jonathan De Roo, Matthew W. Greenberg, Brandon M. Mcmurtry, Mark P. Hendricks, Ellie Bennett, Natalie Saenz, Matthew Y. Sfeir, Benjamin Abecassis, Sanjit K. Ghose, Jonathan S. Owen
Advanced Science Research Center
A library of thio- and selenourea derivatives is used to adjust the kinetics of PbE (E = S, Se) nanocrystal formation across a 1000-fold range (kr = 10−1 to 10−4 s−1), at several temperatures (80–120 °C), under a standard set of conditions (Pb : E = 1.2 : 1, [Pb(oleate)2] = 10.8 mM, [chalcogenourea] = 9.0 mM). An induction delay (tind) is observed prior to the onset of nanocrystal absorption during which PbE solute is observed using in situ X-ray total scattering. Density functional theory models fit to the X-ray pair distribution function (PDF) support a Pb2(μ2-S)2(Pb(O2CR)2)2 structure. Absorption spectra …
Statistical Measurements Of Dispersion Measure Fluctuations Of Frbs, Siyao Xu, David H. Weinberg, Bing Zhang
Statistical Measurements Of Dispersion Measure Fluctuations Of Frbs, Siyao Xu, David H. Weinberg, Bing Zhang
Physics & Astronomy Faculty Research
Extragalactic fast radio bursts (FRBs) have large dispersion measures (DMs) and are unique probes of intergalactic electron density fluctuations. By using the recently released First CHIME/FRB Catalog, we reexamined the structure function (SF) of DM fluctuations. It shows a large DM fluctuation similar to that previously reported in Xu & Zhang, but no clear correlation hinting toward large-scale turbulence is reproduced with this larger sample. To suppress the distortion effect from FRB distances and their host DMs, we focus on a subset of CHIME catalog with DM < 500 pc cm-3. A trend of nonconstant SF and nonzero correlation function (CF) at angular separations θ less than 10 is seen, but with large statistical uncertainties. The difference found between SF and that derived from CF at θ ≲ 10 can be ascribed to the large statistical uncertainties or the density inhomogeneities on scales on the order of 100 Mpc. The possible correlation of electron density fluctuations and inhomogeneities of density distribution should be tested when several thousands of FRBs are available.
Reinvigorating A Technical Countering Weapons Of Mass Destruction Distance Learning Graduate Certificate Program, James C. Petrosky, Gaiven Varshney, Jeremy Slagley, Sara Shaghaghi
Reinvigorating A Technical Countering Weapons Of Mass Destruction Distance Learning Graduate Certificate Program, James C. Petrosky, Gaiven Varshney, Jeremy Slagley, Sara Shaghaghi
Faculty Publications
Current Countering Weapons of Mass Destruction (CWMD) demands can be divided broadly into policy and science. The science of chemical, biological, and radiological/nuclear weapons informs the limits of development, production, employment, operation, detection, risk characterization, human and material protection, and medical intervention. In short, the science of weapons of mass destruction (WMD) should precede and inform the development of policy. It is to this end that the Air Force Institute of Technology (AFIT) CWMD program was re-established, providing a technical educational option for practitioners to understand the science behind a very technically challenging subject.
Free-Free Absorption In Hot Relativistic Flows: Application To Fast Radio Bursts, Esha Kundu, Bing Zhang
Free-Free Absorption In Hot Relativistic Flows: Application To Fast Radio Bursts, Esha Kundu, Bing Zhang
Physics & Astronomy Faculty Research
Magnetic flares create hot relativistic shocks outside the light cylinder radius of a magnetized star. Radio emission produced in such a shock or at a radius smaller than the shock undergoes free–free absorption while passing through the shocked medium. In this work, we demonstrate that this free–free absorption can lead to a negative drift in the frequency-time spectra. Whether it is related to the downward drift pattern observed in fast radio bursts (FRBs) is unclear. However, if the FRB down-drifting is due to this mechanism then it will be pronounced in those shocks that have isotropic kinetic energies ≳1044 erg. …
A Proposed Change To Astronaut Exposures Limits Is A Giant Leap Backwards For Radiation Protection, Francis A. Cucinotta, Walter Schimmerling, Eleanor A. Blakely, Tom K. Hei
A Proposed Change To Astronaut Exposures Limits Is A Giant Leap Backwards For Radiation Protection, Francis A. Cucinotta, Walter Schimmerling, Eleanor A. Blakely, Tom K. Hei
Health Physics and Diagnostic Sciences Faculty Research
Addressing the uncertainties in assessing health risks from cosmic ray heavy ions is a major scientific challenge recognized by many previous reports by the National Academy of Sciences (NAS) and the National Council on Radiation Protection and Measurements (NCRP) advising the National Aeronautics and Space Administration (NASA). These reports suggested a series of steps to pursue the scientific basis for space radiation protection, including the implementation of age and sex dependent risk assessments and exposure limits appropriate for a small population of radiation workers, the evaluation of uncertainties in risk projections, and developing a vigorous research program in heavy ion …
Radium Isotopes As Submarine Groundwater Discharge (Sgd) Tracers: Review And Recommendations, J. Garcia-Orellana, V. Rodellas, Joseph Tamborski, M. Diego-Feliu, P. Van Beek, Y. Weinstein, M. Charette, A. Alorda-Kleinglass, H.A. Michael, T. Stieglitz, J. Scholten
Radium Isotopes As Submarine Groundwater Discharge (Sgd) Tracers: Review And Recommendations, J. Garcia-Orellana, V. Rodellas, Joseph Tamborski, M. Diego-Feliu, P. Van Beek, Y. Weinstein, M. Charette, A. Alorda-Kleinglass, H.A. Michael, T. Stieglitz, J. Scholten
OES Faculty Publications
Submarine groundwater discharge (SGD) is now recognized as an important process of the hydrological cycle worldwide and plays a major role as a conveyor of dissolved compounds to the ocean. Naturally occurring radium isotopes (Ra-223, Ra-224, Ra-226 and Ra-228) are widely employed geochemical tracers in marine environments. Whilst Ra isotopes were initially predominantly applied to study open ocean processes and fluxes across the continental margins, their most common application in the marine environment has undoubtedly become the identification and quantification of SGD. This review focuses on the application of Ra isotopes as tracers of SGD and associated inputs of water …
Radiocarbon And Contextual Data For Non Nok Tha, Don Kok Pho And Don Pa Daeng, Khon Kaen Province, Northeast Thailand, Cyler N. Conrad, Eden Franz, Ernestene Green, Emily Lena Jones
Radiocarbon And Contextual Data For Non Nok Tha, Don Kok Pho And Don Pa Daeng, Khon Kaen Province, Northeast Thailand, Cyler N. Conrad, Eden Franz, Ernestene Green, Emily Lena Jones
Anthropology Datasets
This compendium includes ten documents: 1) the "Buckley Letter" describing the radiocarbon analysis results for sample I-5324, 2) the "GaK-653" sheet describing the radiocarbon analysis results for sample GaK-653, 3) the "GaK-1026" sheet describing the radiocarbon analysis results for sample GaK-1026, 4) the "Geochron Letter" describing radiocarbon analysis results for sample GX-1612, 5) Ernestene Green's ca. 1965 field notes on her test excavations at Don Kok Pho (NP6), 6) Ernestene Green's ca. 1965 field notes on her test excavations at Non Nok Tha (NP7), 7) Ernestene Green's ca. 1965 field notes on her test excavations at Don Pa Daeng (NP8), …
Bis(TetraPhenylArsonium) HexaFluoridoTechnetate(Iv) Dihydrate: Preparation, Structure And Spectroscopic Analysis, Samundeeswari Mariappan Balasekaran, Frederic Poineau
Bis(TetraPhenylArsonium) HexaFluoridoTechnetate(Iv) Dihydrate: Preparation, Structure And Spectroscopic Analysis, Samundeeswari Mariappan Balasekaran, Frederic Poineau
Chemistry and Biochemistry Faculty Research
Reports of quadrivalent transition-metal fluoride salts containing bulky organic cations are limited. In this context, we prepared the bis(tetraphenylarsonium) hexafluoridotechnetate(IV) dihydrate salt, (C24H20As)2[TcF6]·2H2O, by a cation metathesis reaction of (NH4)2[TcF6] in water. This is the first report of an arsonium salt of the hexafluoridotechnetate(IV) dianion. (AsPh4)2[TcF6]·2H2O crystallizes in the triclinic space group P[\overline{1}]. The [TcF6]2− anion adopts a slightly distorted octahedral geometry with an average Tc—F bond length of 1.933 Å. The cyclic voltammogram of (AsPh4)2[TcF6]·2H2O in CH3CN shows a one-electron reversible oxidation wave at 1.496 V.
Nitric Oxide Is Involved In Heavy Ion-Induced Non-Targeted Effects In Human Fibroblasts, Megumi Hada, Premkumar B. Saganti, Francis A. Cucinotta
Nitric Oxide Is Involved In Heavy Ion-Induced Non-Targeted Effects In Human Fibroblasts, Megumi Hada, Premkumar B. Saganti, Francis A. Cucinotta
Health Physics and Diagnostic Sciences Faculty Research
Previously, we investigated the dose response for chromosomal aberration (CA) for exposures corresponding to less than one particle traversal per cell nucleus by high energy and charge (HZE) particles, and showed that the dose responses for simple exchanges for human fibroblast irradiated under confluent culture conditions were best fit by non-linear models motivated by a non-targeted effect (NTE). Our results suggested that the simple exchanges in normal human fibroblasts have an important NTE contribution at low particle fluence. Nitric oxide (NO) has been reported as a candidate for intercellular signaling for NTE in many studies. In order to estimate the …
Pressure-Induced Phase Transition In 1,3,5-Triamino-2,4,6-Trinitrobenzene (Tatb), Brad A. Steele, Samantha M. Clarke, Matthew P. Kroonblawd, I-Feng W. Kuo, Philip F. Pagoria, Sergey N. Tkachev, Jesse S. Smith, Sorin Bastea, Laurence E. Fried, Joseph M. Zaug, Elissaios Stavrou, Oliver Tschauner
Pressure-Induced Phase Transition In 1,3,5-Triamino-2,4,6-Trinitrobenzene (Tatb), Brad A. Steele, Samantha M. Clarke, Matthew P. Kroonblawd, I-Feng W. Kuo, Philip F. Pagoria, Sergey N. Tkachev, Jesse S. Smith, Sorin Bastea, Laurence E. Fried, Joseph M. Zaug, Elissaios Stavrou, Oliver Tschauner
Geoscience Faculty Research
Determining the unreacted equation of state of 1,3, 5-triamino-2,4,6-trinitrobenzene (TATB) is challenging because it exhibits low crystal symmetry and low X-ray scattering strength. Here, we present the first high-pressure single-crystal X-ray diffraction (SXD) study of this material. Our SXD results reveal a previously unknown transition to a monoclinic phase above 4 GPa. No abrupt change of the volume occurs but the compressibility changes. Concomitant first principles evolutionary crystal structure prediction USPEX calculations confirm this transition and show that it involves a pressure-induced in-plane shift of the layers of TATB molecules with respect to the ambient-pressure phase.
Radium Dial Watches, Zainab Alzoubi
Radium Dial Watches, Zainab Alzoubi
Natural Sciences Student Research Presentations
This slide presentation for the Natural Sciences Poster Session at Parkland College summarizes the history of radium dial watches, including the Radium Girls, and explores whether radium dial watches might still be dangerous.
Irene Joliot-Curie, Erick J. Klein
Irene Joliot-Curie, Erick J. Klein
Natural Sciences Student Research Presentations
This poster for the Natural Sciences Poster Session at Parkland College features chemist Irene Joliot-Curie, one of four women, including her mother, Marie Curie, who have won the Nobel Prize for Chemistry. Joliot-Curie, with her husband Frederic Joliot-Curie won the prize in 1935 for their discovery of artificial radioactivity.
Feasibility Of The Use Of Neutron Activation Analysis Techniques In An Underwater Environment, Michael D. Chick
Feasibility Of The Use Of Neutron Activation Analysis Techniques In An Underwater Environment, Michael D. Chick
Masters Theses & Specialist Projects
Elements when bombarded with neutrons emit a gamma ray that is characteristic of the isotope that underwent a neutron induced nuclear reaction; this is known as neutron activation. The characteristic gamma energy of an isotope can then be detected and recorded. One can then analyze the gamma energies captured and determine the elemental makeup of the sample. This form of analysis can be used in an underwater environment making it potentially a valuable tool for agencies tasked with maritime security of ports and waterways, or clean-up operations. This thesis will focus on the feasibility of neutron interrogation using pulsed fast/thermal …
Plutonium Immobilization And Mobilization By Soil Organic Matter, Peter H. Santschi, Kathleen A. Schwehr, Chen Xu, Matthew Athon, Yi-Fang Ho, Patrick G. Hatcher, Nicole Didonato, Daniel I. Kaplan
Plutonium Immobilization And Mobilization By Soil Organic Matter, Peter H. Santschi, Kathleen A. Schwehr, Chen Xu, Matthew Athon, Yi-Fang Ho, Patrick G. Hatcher, Nicole Didonato, Daniel I. Kaplan
Chemistry & Biochemistry Faculty Publications
The human and environmental risks associated with Pu disposal, remediation, and nuclear accidents scenarios stems mainly from the very long half-lives of several of its isotopes. The SRS, holding one-third of the nation’s Pu inventory, has a long-term stewardship commitment to investigation of Pu behavior in the groundwater and downgradient vast wetlands. Pu is believed to be essentially immobile due to its low solubility and high particle reactivity to mineral phase or natural organic matter (NOM). For example, in sediments collected from a region of SRS, close to a wetland and a groundwater plume, 239,240Pu concentrations suggest immobilization by NOM …
Uses Of Diaryliodonium Salts And Methods For Their Synthesis, Jordan M. Veness
Uses Of Diaryliodonium Salts And Methods For Their Synthesis, Jordan M. Veness
Department of Chemistry: Dissertations, Theses, and Student Research
Diaryliodonium salts have been studied continuously since the first report of their synthesis in 1894. Diaryliodonium salts are I(III) derivatives that are air- and moisturestable. The reactivity of these compounds resembles the organometallic chemistry of heavy transition metal ions such as Pb(IV), Hg(II), Th(III), and Pd(II). A significant advantage of diaryliodonium salts is that they can carry undergo many of the aryl functionalization reactions of heavy metal organometallic complexes, yet they have little to no toxicity and they are relatively inexpensive to prepare. The DiMagno laboratory uses diaryliodonium salts as precursors in the final synthetic step of radiopharmaceuticals; given that …
Green Chemistry As A Tool For Understanding The Toxic Substances Control Act: A Lecture Module For Undergraduate Students, Molly R. Blessing
Green Chemistry As A Tool For Understanding The Toxic Substances Control Act: A Lecture Module For Undergraduate Students, Molly R. Blessing
Honors Scholar Theses
The Toxic Substances Control Act (TSCA) is the central form of chemical regulation existent in the United States today, yet scientists are often unaware or uncertain of its provisions. Violations of TSCA by unknowing chemists set industry and government unnecessarily at odds. A lecture on TSCA was developed for undergraduate students that uses the concept of green chemistry to promote interest and incentivize learning. Green chemistry methods are cleaner and less wasteful than traditional chemical ones, and many companies using them are at the forefront of technological innovation. The lecture explains both green chemistry and TSCA, includes company case studies, …
Resin-Supported Arylstannanes As Precursors For Radiolabeling With Iodine: Benzaldehydes, Benzoic Acids, Benzamides, And Nhs Esters, Mustafa Janabi, Catherine M. Pollock, Ann-Marie Chacko, Duncan H. Hunter
Resin-Supported Arylstannanes As Precursors For Radiolabeling With Iodine: Benzaldehydes, Benzoic Acids, Benzamides, And Nhs Esters, Mustafa Janabi, Catherine M. Pollock, Ann-Marie Chacko, Duncan H. Hunter
Chemistry Publications
A highly cross-linked polystyrene resin bearing a reactive chlorostannane moiety 1 has been used to generate a variety of arylstannane radiopharmaceutical precursors for no-carrier-added radioiodination. The resins were characterized for their solvent compatibility and sensitivity to acid cleavage. Resin-supported arylstannanes synthesized via their aryl lithium analogues include 3- and 4-stannylbenzaldehydes, 3- and 4-stannylbenzoic acids, and 3- and 4-N-succinimidyl benzoates. A three-step route to the resin-supported stannylbenzoic acids 12a/b was developed through resin-supported benzaldehydes 11a/b. The aldehyde to acid conversion efficiency is >90%, and acid loading capacities of 0.66–0.94 mmol/g were obtained. Resin-supported N-succinimidyl benzoates 16a/b …
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
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 …
Synthesis: What We Have Learned From The East Texas Radiocarbon Database, Robert Z. Selden Jr., Timothy K. Perttula
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.
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.
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
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).