Research into chemical separation techniques for production of Bi-213 via irradiation of Ra-226 [abstract]

Abstract only availableBismuth 213 is an alpha radioimmunotherapeutic agent used in cancer treatment. Neutron bombardment of radium 226 is being investigated as an alternative method of producing Bi-213. For this project, a literature search of existing chemical separation steps for the production of Bis-213 for radioimmunotherapy was performed in order to optimize the combination of irradiation schemes with chemical separation steps. For the first step, the separation of actinium and radium from thorium 229 and recovery of radium for further irradiation, several successful methods were described in the literature. Organic cation exchange columns such as AG50W-X8 have traditionally been used to perform this step, but these suffer high radiolysis, which newer methods have tried to address. Some of these are an extraction chromatography method using a UTEVA column followed by a RE-resin column on a silica gel support, an inorganic titanium phosphate ion exchanger, and sublimation of the anhydrous chlorides of Th-229 and its daughter isotopes performed in a quartz tube, featuring complete separation of the elements while radium is retained at the bottom of the tube and available for further irradiation in one step. For the second part of the process, the elution of Bis-213 from an Ac-225 generator, quite a few successful techniques are described in the literature. Some of the better ones found are a multicolumn selectivity inversion generator, a renewable column, tandem column extraction chromatography, a PNNL automated generator, a MSKCC generator, an inorganic hydrated zirconium cation exchanger, and silica based resins, as well as the more traditional organic cation and anion exchange columns. A method using alpha recoil of Bis-213 from Ac-225 incorporated into a sealed isotope generator has the benefit of resulting in no radioactive, chemical, or mixed wastes, in contrast to chemical separation methods. In conclusion, several promising separation techniques were found in the literature

Effects of washings and treatments on the usefulness of hair as a biomarker

Abstract only availableHair is a useful matrix for the analysis of many trace elements found in the human body. Studies show that hair can incorporate trace metals into its structure during the growth process. Hair is an attractive monitor because unlike blood serum and urine, it is a metabolic end product and therefore inert. It is collected non-invasively, easily stored and disposed. Many studies in the literature attempt to correlate trace elements measured in hair to health, pollution exposure or to disease. Trace elements in hair can be accurately measured by Instrumental Neutron Activation Analysis (INAA). Hair samples must be cleaned before analysis to remove external contamination, there are many methods of sample cleaning, however there is not a standardized washing procedure. This study investigates pre and post collection cleaning techniques that may alter observed trace element concentrations in the hair. Two separate, post collection washing methods were studied: the International Atomic Energy Agency, IAEA, method, and the University of Missouri Research Reactor, MURR, method. The samples were then analyzed for Se, Ti, Mg, Mn, V, I and Zn using INAA at MURR. Selenium concentrations were unchanged. However, all other elements showed a significant reduction in concentration from the MURR to the IAEA method. It was also hypothesized that pre-collection cleaning with shampoos containing EDTA, a chelating agent, may be responsible for leaching some trace metals from hair. In order to determine the effects of shampoos on the sample, hair from a single subject was treated with three different types of shampoo. Two solutions of each shampoo were prepared in a 1:4, shampoo:water ratio. The hair was then washed in these solutions for either 1 or 24 hours for each type of shampoo. Hair washed with shampoo containing selenium sulfide resulted in a large selenium contamination despite cleaning with both the IAEA and MURR methods. The large variability between the post-collection cleaning techniques shows that a standard preparation method must be established before hair can be accurately used as a biomarker. Further studies must be done to determine if pre-collection shampoo treatment affects the validity of hair as a biomarker for trace elements.NSF-REU/NIH Program in Radiochemistr

Neutron activation analysis of mercury in petroleum distillates

Abstract only availableIn liquefied natural gas (LNG) plants and nitrogen rejections units (NRU) that utilize aluminum heat exchangers, mercury (Hg) contaminates can result in corrosion of equipment, poisoning of catalysts, mechanical failure, and gas leakage. The purity of the product streams from these plants is also important due to the fact that many of the resulting products such as naphtha are used as feedstock for ethylene production and various solvents. Analytical methods such as chemical extractions (CE), combustion/trap (CT), atomic fluorescent spectrometry (AFS), and inductively coupled plasma optical emission spectrometry (ICP-OES) have been used to measure mercury in petroleum distillates. These methods require extensive sample preparation. A mercury analytical method that can be applied to distillates in routine operation that minimizes mercury loss from sampling preparation is needed. Neutron Activation Analysis (NAA) is a sensitive analytical technique that can be applied to samples as received. The objective of this work was to develop a NAA procedure for testing Hg in naphtha. Virgin naphtha samples were spiked with Hg at concentrations of 20, 50, 200, 500, 1000 and 1500 ng/g. One set of samples were prepared 3 days prior to irradiation and the second set was prepared and irradiated the same day. Analysis of the samples proved that even at small samples sizes (~800 µl) concentrations of 50 to 1500 ng/g of mercury in naphtha are easily detected and give a linear response. Samples that were prepared and irradiated on the same day showed less Hg loss than those prepared 3 days prior to irradiation. Analysis of multiple (n=5) 200 ng/g samples yielded a precision of 9% RSD. The minimum detectable amount of Hg using this technique is 5 ng.NSF-REU Radiochemistr

Analyzing the effects of lactose on calcium absorption in premature infants using HR-ICP-Mass Spectrometry

Abstract only availableWith advances in neonatal care, premature infants are surviving at increasing rates. During the third trimester of pregnancy, the bone mineral content of infants rapidly increases. It is therefore becoming essential to accurately mimic the womb environment to maintain growth and sustain the health of premature infants as if they were in utero. Regulating calcium absorption in premature infants is crucial primarily for bone formation, as 99% of the calcium in the human body is found in the bones and the teeth. The effect of lactose containing formulas on calcium absorption in premature infants has not been well established. Concerns have been noted in the scientific community regarding lactose intolerance especially in premature infants, as lactase, the enzyme responsible for lactose digestion, is most readily detectible during the third trimester of pregnancy. In this study, in conjunction with Dr. Laura Hillman of the University of Missouri Hospital, each infant was fed lactose and maltose formulas during different weeks using a dual tracer method in which two calcium isotopes were administered, 44Ca orally and 46Ca intravenously. Urine samples were collected after 24 hours. Analysis related natural abundances of calcium isotopes to the measured values in the urine. Polyatomic ion interferences were differentiated from the calcium peaks by analyzing the samples at a resolution of 4000. Mathematical corrections for interferences caused by titanium and doubly charged strontium were determined by measuring the specific isotopes 47Ti and 87Sr++ and using known natural abundances of the interfering isotopes to correct each calcium count rate. Mathematical calculations relate the enriched isotope ratio measurements of 44Ca and 46Ca to calcium absorption. Analysis regarding the effect of lactose on calcium absorption is ongoing. Our data precision on the ICP-MS was acceptable with percent relative standard deviations (%RSD) for external precision over the course of a week at 1.4, 2.2, 0.71, and 1.4 for isotope ratios 42Ca: 43Ca, 42Ca: 44Ca, 42Ca: 46Ca, and 42Ca: 48Ca respectively. Daily internal precision (%RSD) values were .37, 1.3, .69, and 1.5. The precision shows the viability of utilizing HR-ICP-MS analysis for calcium isotope ratios.NSF-REU/NIH Program in Radiochemistr

Prompt Gamma Neutron Activation Analysis of Alternative Sensor Materials for Planetary Exploration [abstract]

Abstract only availableFaculty Mentor: Dr. William H. Miller, Nuclear Engineering and MURRPrompt gamma-rays from a thermal neutron capture reaction have been used to determine the amount of hydrogen in various materials using the prompt gamma neutron activation analyses (PGNAA) facility at Missouri Research Reactor (MURR). PGNAA uses an intense neutron beam from a nuclear reactor to measure the concentration of certain elements, including Fe, Ni, B and H. In our research, we used samples of diamond powder, a stainless steel disk and construction bolts. Half of the samples in each group were treated with either a hydrogen or a nitrogen plasma in the plasma laboratory at Polytechnic University of Puerto Rico (PUPR) while the other half remained untreated as controls. A urea SRM was used as a standard while a titanium sample was repeatedly utilized for measuring the variation in neutron flux which is a density measurement of the neutrons passing though a given region of space. The measured concentration of hydrogen present will reflect the efficiency of absorption of the substrate to hydrogen generated in the plasma. We hope to develop substitute sensor materials which will be used for planetary exploration as well as other uses for hydrogen or nitrogen impregnated substrates from plasma fields.Department of Energy's Innovations in Nuclear Infrastructure and Education Progra

N/P ratio in the PEI2-GNP-DNA complex affects transgene delivery in the human cornea in vitro

Recently, we discovered that polyethylenimine-conjugated gold nanoparticles (PEI2- GNP) could be used as gene therapy vector for the cornea. It was hypothesized that DNA concentration, incubation timing and PEI monomer amount in transfection solution affect gene transfer efficiency and toxicity. The aims of this study were to test whether molar ratio of PEI2 nitrogen (N) and phosphate (P) of DNA in PEI2-GNP transfection solution regulates transgene delivery in human corneal fibroblasts in vitro, and examine PEI2-GNP toxicity, uptake and clearance for the cornea in vivo."National Eye Institute, NIH, Bethesda for RO1EY017294 (RRM), Diversity (RRM) and Veteran Health Affairs Merit (RRM) grants and Unrestricted grant from Research to Prevent Blindness, New York

Photovoltaic and Betavoltaic Efforts at University of Missouri-Columbia

Track III: Energy InfrastructureIncludes audio file (23 min.)Photovoltaic device converts solar energy into electricity by the photovoltaic effect. Efficiency of a photovoltaic device depends on the active material which absorbs light as well as the window layer which transmits light into the active layer. High band gap window layer allows majority of light to transmit from the solar spectrum while active layer has an optimum value for maximum efficiency. We have carried out research on amorphous silicon as an active conversion layer which has a larger band gap and higher light sensitivity than crystalline Si for photovoltaic device, while high band gap zinc oxide (ZnO) can serve as window layer. Betavoltaic device is analogous in principle to a photovoltaic and the difference is that it is specifically designed to convert energy from beta particles rather than photons. Nano crystalline silicon-carbide (SiC) and ZnO are some of the ideal candidates for betavoltaic devices because of its high band gap and radiation hardness. Both of them are also sensitive to light, so potentially they can be used to fabricate photovoltaic devices. Present betavoltaic devices based on SiC are not cost effective as SiC requires high temperature process. We were able to achieve SiC films at a low temperature process by converting amorphous SiC into crystalline SiC using aluminum induced crystallization technique. The films were characterized by FTIR, TEM, UV-Vis spectroscopy, Hall measurements and I-V measurements. The p-n junctions are fabricated by depositing p-type SiC layer on n-type substrates. For successful fabrication of betavoltaic device, high quality n-ZnO films are deposited and characterized by Raman spectroscopy, XRD, UV-Vis spectroscopy, Hall measurements, I-V and photoconductivity measurements. ZnO based p-n junctions are fabricated by depositing ZnO (n-type) layer on p-type Si substrate, and the rectifying behaviors were observed. For proof of concept a betavoltaic device was fabricated and tested with beta particle

Merritt Lyndon Fernald correspondence,

Correspondenc