W. D. James

Compositional analysis of American southwestern ceramics by neutron activation analysis

Instrumental neutron activation analysis was used to perform compositional analysis on more than 200 potsherds from prehistoric ceramic pottery collected in or near the Mimbres Valley in New Mexico. Statistical evaluation of the data was used to identify samples of similar origin. Results indicate that at least two sites within the Mimbres heartland and one in the Upper Gilla Valley existed for the production of the characteristic Classic Mimbres pottery. The composition of the clusters of samples identified are described and the significance of the groupings to the archaeology of the region is discussed.

INAA multielemental analysis of Nigerian bituminous coal and coal ash

Instrumental neutron activation analysis (INAA) was used to analyzed Nigerian bituminous coal and ash. Good statistical agreement (p≤0.05) between the literature and reported elemental values of USGS AGV-1 sample was found. Many elements were determined in the coal with some enrichment in the coal ash. Arsenic was measured only in the ash while Hg was present only in the coal. Coal ashing at 800°C contributed to a loss of Hg in the ash. Al, Na, Mg, Ti, Fe, which are major elements were found in the coal as expected, with slight enrichment in the ash. Ca and Si were only obtained in the ash. High ash Al (14.9±0.19%) and Si (25.3±4.11%) levels are of concem due to possible cases of pneumononiosis from inhalation of the particulates. Graphical illustration of the lanthanide concentrations peaked at Ce with a decrease from Sm to Lu. U and Th were also present in the samples showing slight enhancement in the ash. Comparatively low coal elemental values, notably S(1.8%), highly advocate this coal as a good quality fuel-coal.

Ocean-sediment analysis by neutron activation

Neutron activation analysis (NAA) techniques have been developed and applied to the analysis of marine sediments. More than 150 core sites have been sampled in the northwestern Gulf of Mexico. More than 500 surface and subsurface sediment samples have been analyzed for Ba, Cr, Fe, and various other elements of interest. Typical concentrations at various locations are given. An extensive half-life study was performed to verify that gamma lines, used for quantitation exhibited the decay parameters expected to the parent radionuclide. Suggested gamma lines are presented for a few elements of particular interest to ocean-sediment analysis.

Murine photoplethysmography for in vivo estimation of vascular gold nanoshell concentration

There is an urgent clinical need to monitor the intravenous delivery and bioavailability of circulating nanoparticles used in cancer therapy. This work presents the use of photoplethysmography for the noninvasive real-time estimation of vascular gold nanoshell concentration in a murine subject. We develop a pulse photometer capable of accurately measuring the photoplethysmogram in mice and determining the ratio of pulsatile changes in optical extinction between 805 and 940 nm, commonly referred to as R. These wavelengths are selected to correspond to the extinction properties of gold nanoshells. Six 30-s measurements (5 min, 2, 4, 6, 8, 10 h) are taken under light anesthesia to observe the change in R as the nanoparticles clear from the circulation. Our model describes the linear fit (R(2)=0.85) between R and the concentration of nanoparticles measured via ex vivo spectrophotometric and instrumental neutron activation analysis. This demonstrates the utility of this technique in support of clinical nanoparticle therapies.

Compton suppression gamma-spectroscopy in the analysis of radium and lead isotopes in ocean sediments

Compton suppression gamma-spectroscopy provides an efficient method for measuring the concentration of226Ra,228Ra, and210Pb in ocean sediments. The background reduction realized from the suppressed mode of operation provides an “active shield” to allow for the low-level counting required for these measurements. We have used the method to study the possible accumulation of radium from produced waters in sediments from Gulf of Mexico sites of varied distances from drill platforms. In addition,210Pb levels were determined to evaluate the use of our spectrometer for this purpose. Baseline undisturbed concentrations have been obtained from the study of subsurface core material which predates drilling activities. Correlations of radium isotope concentrations with iron and barium provide information concerning the possible relationships between radium levels and drilling activity (excess barium) and natural variations in sediment texture (iron).

Application of prompt gamma activation analysis and neutron activation analysis to the use of samarium as an intestinal marker

The use of prompt gamma activation analysis (PGAA) as a method for detection of the intestinal rare earth marker, samarium, has been evaluated by comparison with thermal neutron activation analysis (NAA). PGAA detection has significant advantages with respect to its higher reaction cross section and possible rapid experimental turnaround time. Serious disadvantages are lower neutron fluxes available to the target and nonavailability of numerous PGAA facilities. Results of the technique comparisons are generally very good. Pony fecal concentrations of samarium in samples obtained at various times after administration of a marked meal were measured by both techniques. In only one sample did results of the methods differ by more than the experimental errors involved.

An instrumental neutron activation analysis of 18th century lead-glazed earthenwares from four Spanish missions in Texas

Instrumental Neutron Activation Analysis (INAA) was used to determine relative manufacturing locales of lead-glazed earthenwares recovered from four Spanish missions in Texas. Two principal clays were distinguished, one containing volcanic ash and one sand. The ceramics characterized by the volcanic ash were believed to have been manufactured in Mexico, while those containing sand were made in Texas. This distinctionis important because it suggests that the Indians at the Texas missions were manufacturing ceramics using Spanish technology such as lead-glazing.

On the determination of phosphorus via charged particle activation analysis

The feasibility of charged particle activation analysis for phosphorus measurements was evaluated. Several nuclear reactions were studied with respect to pertinent activation data, thick target yields for calibration, relative excitation functions, and quantitative importances of interferences. Determination of phosphorus by the reaction31P(α,n)34mCl was determined to be most advantagous with sensitivity competitive with other techniques.

Overcoming Matrix Effects in the 14 MeV Fast Neutron Activation Analysis of Metals

Fast neutron activation analysis (FNAA) has proven to be a useful technique for the estimation of non-metallic inclusions in metals, and is currently being used in industry, especially for the determination of oxygen in magnesium alloys. However, high levels of radioactivity induced in large metallic samples by irradiation in a neutron field give rise to matrix interferences which are significant at low oxygen concentrations. These interferences are due to coincidental summations that fall into the energy window used for quantitation of oxygen. This report explains technical details of newly developed experimental procedures and alterations of existing software which correct for the errors, thereby enhancing the potential for use of the method.

Trace element partitioning in Texas lignite combustion

Trace element partitioning was studied at a pulverized-lignite fired power plant in Texas. Concentrations of 41 elements were determined by neutron activation analysis (NAA) for lignite fuel and combustion effluents collected during 10 consecutive days. Elements studied were grouped into three classes according to their enrichment factors and the relationship between their concentrations and particle size. In general, the concentration enhancement in fly ash and the difference in enhancement between elements placed in different classes are shown to be less significant in this study than for other partitioning studies on higher rank coals.