A complementary use of the comparative and the semi-absolute variations of instrumental neutron activation analysis (INAA) has enabled us to determine 22 different elements in a sample of natural fluorite originating from the younger granite province of Nigeria. The mineral has a brownish purple appearance with some veinlets having a deep purple coloration. Of all the 22 elements measured, Fe (851.36 ppm), Sb (7.69 ppm), Ag (87.4 ppm), Hg (2.71 ppm) and Se (1.97 ppm) are found to be exclusive to the veinlets while Au (109.15 ppm), Co (2.15 ppm) and W (173.20 ppm) are concentrated in the main matrix of the fluorite. With the aid of the semi-absolute method, it was possible to measure the Au concentration in the IAEA Soil-7 reference material to be 56.83±5.87% ppm. A qualitative electron microprobe analysis (EMA) showed that the bulk of the matrix is composed mainly of Ca and F, as expected.

To overcome the deficiencies of positron emission tomography and single photon emission computed tomography due to photon scatter and absorption artifacts, we identified a better approach of employing single isotopes which are positron emitters as well as gamma emitters. Tomography with a single isotope affords 3-D vertex reconstruction of each event and thus provides vastly improved images. We evaluated 116 positron and gamma emitting nuclear isotopes for their half-lifes, photon energies and intensities, ease and economy of production and biological compatibilities. ⁷³Se, ⁹⁹Rh, ¹²³Xe, ¹⁷⁴Ta and ¹⁸⁴Ir are identified as most promising candidate isotopes.

Studies have shown that plots of the log of the distribution ratio versus pH for the distribution of uranium(VI) between non-plasticized and TBP-plasticized dibenzoylmethane-loaded polyurethane foams and dilute aqueous uranium(VI) solutions have a limiting slope of 0.6 at equilibrium pH values ≤4 and reach a maximum distribution constant at about pH 6.0. The results indicate that the extracted complex is a simple chelate, UO₂Me₂, where HMe denotes dibenzoylmethane. Plasticization of the foam with TBP has been found to significantly enhance the rate of extraction.

A preliminary test of a liquid mercury target for the production of neutrons by spallation was undertaken at the Alternating Gradient Synchrotron facility at Brookhaven National Laboratory. Neutron activation of elemental foils placed on the target demonstrates that a range of neutron energies does exist, as expected, and that the neutron flux is at a maximum 10–20 cm from the front of the target, moving deeper with increasing proton energy. Uncertainties in the activity calculations are in general significantly <10%. Impurities in some of the foils are a significant source of interference for some reactions, although there is no interference for most of the reactions. The presence of many interference-free reactions, along with the low uncertainties indicates that the foils will be useful benchmarks to validate the neutronics codes utilized in the target design.

The neutron temperature is a characteristic parameter in irradiation channels of reactor. For nuclides which have resonances in the thermal neutron energy range, their Westcott g-factors are different from unity. The values of g-factors and cross-sections of (n, γ) reaction of these nuclides are temperature dependence. The standard energy for tabulation of thermal neutron cross-section (σ₀) is that of room temperature (293.59 K or 20.43 °C), corresponding to a neutron energy 0.0253 eV or to a neutron velocity of 2200 m/s. However, in the irradiation channels of reactor, the temperature is not exact at 20.43 °C. Thus, the temperature at the irradiation position must be known to convert σ₀ to σ(T). A method for determination of the neutron temperature in irradiation channels of Dalat reactor is presented by fitting the thermal neutron spectrum obtained from the calculation using MCNP code.

Whole blood from patients undergoing Coronary Artery Bypass Grafting (CABG) operations was separated into leukocyte subfractions of polymorphonuclearcytes (PMN) and peripheral blood mononuclear cells (PBMC). Blood samples were collected and analyzed at various timepoints to determine the elemental composition to provide a better understanding of recovery mechanisms and to indicate complications that may occur post-operatively. Proton induced X-ray emission (PIXE) analysis and Rutherford backscattering spectrometry (RBS) using the University of Surrey microprobe was employed to determine the concentrations of a range of elements. Accurate two-dimensional PIXE analysis however, requires knowledge of the sample matrix composition. These samples, on the other hand, showed varying thickness, lacked matrix homogeneity and displayed non-uniform trace element distribution. This paper discusses the results and problems associated with routine PIXE analysis and demonstrates the potential ability of ion beam analysis (IBA) depth profiling software, previously unused in PIXE analysis, to model a RBS spectrum of inhomogeneous, multi-layered samples prior to performing PIXE analysis.

Iodine is an essential nutrient in the human diet. Its primary role is expressed as a component of thyroxine (T4) and the corresponding deiodinated triiodothyronine (T3) hormones produced by the thyroid as part of the system that regulates growth, mental development and metabolism. The recommended daily allowance (RDA) for iodine ranges from 50 μg/day for infants to 150 μg/day for adults. Reports over the last 15 years have indicated that the U.S. diet provides 2 to 7 times the iodine RDA and that dairy products typically provide 20 to 60 percent of the dietary iodine intake. Measurements of iodine in dietary components and composites reported in FDA studies have been done calorimetrically. These studies have, according to the authors, both under reports (by up to −50%) and over reports (by up to +80%) the iodine, depending on food type, compared to a radiochemical NAA reference method. Milk is typically under reported by −20%. The objective of this study was to utilize epiboron neutron activation analysis (EBNAA) to study the iodine concentrations, and seasonal variations of iodine, and market milk and infant formula, collected 15 years apart, in comparison with the Food and Drug Administration (FDA) market-basket reports.

An ammonium carbonate-based process is being developed for the recovery of uranium from the residue generated by an alkaline dissolution process used in the production of the medical isotope ⁹⁹Mo. As a unique application of this dissolution medium, this is the first attempt at uranium recovery from a commercial ⁹⁹Mo production process. Dissolution parameters were optimized with unirradiated residue material and applied to irradiated residue in a small hot cell. Complete recovery of uranium from the residue was achieved with three successive ammonium carbonate/peroxide leaches with final decontamination factors ranging from low values of 1–10 (¹³⁷Cs, ¹⁰⁶Ru, ¹²⁵Sb) to infinity (lanthanides).

It is necessary to develop high-uranium-density targets with low enriched uranium in order to improve ⁹⁹Mo production efficiency. In order to investigate the use of high density low enriched uranium (LEU) dispersion targets using atomized U–Al alloy powder, U–10 wt% Al and U–20 wt% Al powders were fabricated by centrifugal atomization. Metallurgical reactions between uranium and aluminum during the hot working were investigated in order to minimize changes in the established chemical processes for ⁹⁹Mo extraction. It is concluded that LEU based dispersion target plates with increased uranium density can be fabricated by controlling the chemical reactions between U and Al in atomized U–Al alloy powders.

A new versatile solid phase extraction and spectrophotometric determination of uranium (VI) was proposed with using poly(caprolactone-b-vinyl benzyl chloride-g-dimethyl amino ethyl methacrylate), poly(CL-b-VB-g-DMAEMA), amphiphilic brush type block/graft copolymer. The method is based on the adsorption of uranium(VI)-pyrocatechol violet complex on surface on the adsorbent. The parameters such as pH, amount of ligand and copolymer, sample volume were optimized. Detection limit, preconcentration factor and relative standard deviation were found as 0.45 µg L⁻¹, 100 and 3.8 %, respectively. Adsorption capacity of the polymer for uranium(VI) was found 52 mg g⁻¹. The method was applied to different water samples and standard reference materials.