Simultaneous PIXE/PIGE was used to determine the concentration of 20 elements including N, O, F, Na, Mg, P, Ca (PIGE) and Cr, Mn, Cu, Zn, Cd, Ba, Pb (PIXE) in a number of animal and human rib samples, marrow, and the IAEA CRM Animal Bone (H-5). Samples and standards were bombarded with 2.5 and 4.0 MeV external proton beams. The minimum detection limits for most of the minor and trace elements ranged from 0.5 to 1.5 ppm. The sample preparation procedure for the nondestructive instrumental analysis of bone is discussed in detail. The analysis method is fast, nondestructive and offers selective analysis of the cortical and cancellous surface of the same bone sample.
A method is described for the preparation of an electrodeposited mount of plutonium that makes possible the performance of
both alpha-energy and mass measurements on the single mount. Plutonium concentration and isotopic composition are obtained
from the measurement data.
We present the outline of a comprehensive website based offering of a basic graduate level or senior undergraduate level course in nuclear and radiochemistry. This password protected course follows classical pedagogical treatment of the subject. However, it has been augmented by the implementation of Flash animations to better teach basic nuclear and radiochemistry concepts. As well, the website is linked to many Internet related resources. All lectures and problems are presented in Microsoft Power Point format with Flash animations incorporated. A series of six experiments in radiochemistry, also offered in the course is available in a downloadable Microsoft Word format.
Authors:D. Robertson, D. Haggard, C. Thomas, and N. Wynhoff
Three different methods for determining the long-lived radionuclide contents of highly neutron activated metal wastes are being compared and assessed using samples of pressurized-water reactor (PWR) and boiling-water reactor (BWR) spent fuel disassembly hardware and control rods. These methods include: 1) empirical analyses involving sampling and laboratory measurements; 2) direct assay techniques; 3) calculation methods. These techniques are discussed and the results of the comparisons made to date are presented. The agreement between empirical versus calculational methods for the disassembly hardware was generally within 10% to 50%, and rarely exceeded a factor of 2.5, especially near the fueled region of the reactor core. However, large discrepancies between the measured versus calculated concentrations were observed for59Ni and63Ni at the end fittings of the fuel assembly hardware, where the calculations underestimated the concentrations by factors varying from about 8 to 28. The calculation errors are believed to be due to inadequate cross section data for the nickel isotopes.
Authors:E. Lepel, S. Pratt, D. Robertson, C. Thomas, and D. Haggard
Three different spent control rods were obtained for direct-assay measurements and empirical sampling and analysis. They were: 1) a BWR cruciform control rod, 2) a PWR rod-cluster control assembly, and 3) a burnable poison-rod assembly. The dominant activity of the BWR cruciform control rod and the PWR burnable poison-rod assembly is60Co, whereas the PWR rod-cluster control assembly is dominated not only by60Co, but also by108mAg and110mAg, which are found in the Ag–In–Cd alloy of the absorber rods. The radionuclide inventories calculated for the three spent control rods from the empirical sampling data agree very well with data determined from the two direct assay methodologies. The concentration of108mAg in the rod-cluster control assembly will have to be considered when these types of spent control rods are prepared for waste disposal.
Authors:D. Meier, A. Garnov, J. Robertson, J. Kwon, and T. Wacharasindhu
The specific energy density from radioactive decay is five to six orders of magnitude greater than the specific energy density
in conventional chemical battery and fuel cell technologies. We are currently investigating the use of liquid semiconductor
based betavoltaics as a way to directly convert the energy of radioactive decay into electrical power and potentially avoid
the radiation damage that occurs in solid state semiconductor devices due to non-ionizing energy loss. Sulfur-35 was selected
as the isotope for the liquid semiconductor demonstrations because it can be produced in high specific activity and is chemically
compatible with known liquid semiconductor media.
Authors:H. Gersch, J. Robertson, A. Henderson, D. Pollack, and C. Munson
Particle-induced X-ray emission (PIXE) spectrometry is being used to nondestructively determine the elemental composition
of copper-based artifacts excavated from prehistoric/protohistoric sites in the Ohio River Valley. Copper objects from Caborn-Welborn
(C-W) and contemporary Fort Ancient sites are being studied so as to differentiate between native American and European copper.
The trace element analysis of metal artifacts enables archaeologists to more accurately assess the material culture and chronological
development of C-W society (A.D. 1400–1700) with particular reference to geological sources of copper and brass.
Authors:K. Thomson, S. C. Hunter, S. H. Butler, and D. J. Robertson
Background and aims
Social media use has become a ubiquitous part of society, with 3.8 billion users worldwide. While research has shown that there are positive aspects to social media engagement (e.g. feelings of social connectedness and wellbeing), much of the focus has been on the negative mental health outcomes which are associated with excessive use (e.g. higher levels of depression/anxiety). While the evidence to support such negative associations is mixed, there is a growing debate within the literature as to whether excessive levels of social media use should become a clinically defined addictive behaviour.
Here we assess whether one hallmark of addiction, the priority processing of addiction related stimuli known as an ‘attentional bias’, is evident in a group of social media users (N = 100). Using mock iPhone displays, we test whether social media stimuli preferentially capture users' attention and whether the level of bias can be predicted by platform use (self-report, objective smartphone usage data), and whether it is associated with scores on established measures of social media engagement (SMES) and social media ‘addiction’ severity scales (BSNAS, SMAQ).
Our findings do not provide support for a social media specific attentional bias. While there was a large range of individual differences in our measures of use, engagement, and ‘addictive’ severity, these were not predictive of, or associated with, individual differences in the magnitude of attentional capture by social media stimuli.
More research is required before social media use can be definitively placed within an addiction framework.
Authors:A. E. Veatch, J. D. Brockman, V. L. Spate, J. D. Robertson, and J. S. Morris
Selenium is a required trace-element that has been found to be protective against serious chronic diseases such as cancer and cardiovascular disease in some, but not all, epidemiological studies using both case-control and intervention designs. As a result, the fraction of the adult U.S. population now taking a daily selenium supplement is steadily increasing. In this study, we analyzed 10 or more replicate Se supplement tablets, from each of 15 different products representing 12 different brand names with most being sampled at two different times separated by approximately 30 months. Two chemical forms, seleno-yeast and selenate were tested in 50, 100 and 200 µg/tablet dosages (seleno-yeast) and 25 and 200 µg/tablet dosages (selenate). Variations in contemporary lots were evaluated at both sampling periods. The Se content provided on the product label is generally understated. One tablet contained 2.5 times more selenium than the stated dose. Selenate supplements are less accurately labeled and more highly variable compared to yeast supplements. One popular multivitamin, labeled at 200 µg/tablet, contained tablets in excess of 300 µg. Many subjects using this supplement will exceed the 400 µg/day tolerable upper limit of intake, recently established, for Se by the Institute of Medicine’s Food and Nutrition Board.
Authors:J. Terry, B. Grzenia, D. Papagiannopoulou, J. Kyger, S. Jurisson, and J. D. Robertson
99mTc compounds play a very important role in modern medicine. These compounds are among the most widely used radiopharmaceuticals. Unfortunately, due to the necessity of working with small quantities of materials, the chemistry of these materials is not completely understood. Currently, the structure of the 99mTc-DTPA (a common renal imaging agent) is unknown. In this paper, we show that X-ray absorption spectroscopy (XAS) can be used to determine the structure of Tc ycompounds b comparing XAS results to those from X-ray diffraction (XRD). Specifically, XAS data and fits for TcCl62-, TcOCl4-, and TcNCl4- were found to be in excellent agreement with the known structures from XRD. Finally, we show the XAS spectrum from a 77 ng sample of 99Tc-DTPA. To our knowledge this is the first XAS spectrum taken from this material. The near-edge region (XANES) was visible after a single scan on this material. This clearly indicates that we will be able to determine the local atomic structure of this material.