Authors:C. Baskett, V. Spate, M. Mason, C. Reams, and J. Morris
The selenium excreted in urine can be measured to assess the dietary status of selenium, an essential trace element in human nutrition. The objectives of this work were: 1) to develop a procedure, capable of high sample throughout, by which the major interferences can be reduced such that selenium concentrations can be measured in urine by Neutron Activation Analysis (NAA) using77mSe (17.4 s; and 2) to apply the method to a human dietary selenium study in which several selenium monitors were compared. The method involves a pre-irradiation arsenic-coprecipitation separation of the selenium from urine in the presence of a high specific-activity75Se tracer. The processed urine samples are analyzed using NAA. The procedure was applied to 58 urine specimens longitudinally collected from 12 subjects consuming three different levels of selenium. A dose-response relationship was observed in urine as well as a high correlations with both serum and whole blood selenium concentrations.
Authors:S. Biegalski, G. Shipman, L. Mason, M. Pickering, and S. Altman
CREWS is a regional network of five high volume air samplers located around the Gulf of Mexico designed to detect extremely low level releases of airborne radioactivity from the nuclear power plants being constructed in Cuba. Four of the stations are currently operational. The CREWS stations use a high efficiency particulate filter to sample aerosols larger than about 10 nm. Aerosols are collected continuously for a week at a flow rate of 515 cubic meters per hour and then counted on a high purity germanium (HPGe) spectroscopy system. The first station began operation in October, 1998. This paper reports the concentration ranges and seasonal trends of the natural radionuclides 7Be and 210Pb detected by the CREWS system. Anthropogenic measurements are also provided and possible sources are discussed. Finally, the paper examines the average minimum detectable concentrations achieved by the systems and predicts the level of release that this system can detect from the Cuban reactors.
Authors:A. Rawson, V. Spate, C. Baskett, M. Mason, and L. Hillman
A chemical and radiochemical neutron activation analysis (CNAA/RNAA) method has been developed for the determination of three
calcium isotopes (48Ca,46Ca, and44Ca) in a single sample derived from urine. This method was developed in support of clinical research using a dual enriched
stable isotope methodology to study bone mineralization in premature infants, juvenile rheumatoid arthritics, and cystic fibrosis.
In these studies, one enriched isotope of calcium is administered orally, and one is administered intravenously. By making
determinations of three isotopes (two enriched, one unenriched) within the same sample, the perturbation from natural isotopic
ratios can be determined and used to calculate true absorption of calcium. In our method,48Ca is determined via the48Ca(n,γ)49Ca reaction and 3084 keV gamma-ray,46Ca via the46Ca(n,γ)47Ca reaction and 1296 keV gamma-ray, and44Ca via the44Ca(n,γ)45Ca reaction and 256 keV (max) beta-particle. A pair of chemical separation steps are employed to separate calcium from urine
as calcium oxalate with a yield in the range of 80–90%, and a radiochemical step is employed prior to the measurement of45Ca to remove interfering radionuclides.
Authors:V. Spate, J. Morris, C. Baskett, M. Mason, C. Reams, D. Hunter, and W. Willett
The role of fluorine in human health has become somewhat controversial. It is widely accepted as protective against dental caries, may be protective against osteoporosis, and has been very conservatively implicated with osteosarcoma in male rats. In this study, we repot on the development of a neutron activation analysis method and its application to the analysis of human nails. We have found that toenails collected in population-based epidemiology studies apparently reflect fluoride intake.
Authors:V. Spate, M. Mason, C. Reams, C. Baskett, J. Morris, and D. Mills
In this study we report on the comparison between the total selenium in serum (total Se) with that which is apparently bound to high molecular weight (>12,000 D) species, presumably proteins (bound Se). Nine hundred seventy seven (977) serum samples arising out of a population-based epidemiological study were prepared in duplicate for the determination of total Se by pipeting directly into irradiation vials; and separate duplicate aliquots were dialyzed against DI water for the determination of bound Se. All samples were analyzed by neutron activation analysis via77mSe (17.4 s). A small dialyzable Se component (6%) (free Se), defined as the difference between the total Se minus the bound Se, was identified.
Authors:C. Tharp, J. Kelly, J. Morris, C. Baskett, V. Spate, M. Mason, T. Cheng, and T. Nichols
Chronic dietary deficiency of selenium has been shown to be associated with degenerative heart disease in production animals
in the U.S. and in the human in parts of China. In the latter, subjects in the endemic areas suffer high rates of a cardiomyopathy
known as Keshan's Disease which is normally fatal in early adulthood and can be prevented, or reversed in its early stages,
via selenium supplementation. Selenium, as the active moiety in the enzyme glutathione peroxidase, protects against oxidative
attack of cell membranes by peroxides formed during normal metabolism. In this study, we investigated the distribution of
selenium in healthy porcine and bovine heart tissue freshly collected at slaughter. The whole heart was perfused with DI water
and carefully de-fatted. Representative samples of left and right atria and ventricles and the interventricular septum were
collected, lyophilized and homogenized prior to preparing replicate samples for analysis. Replicates were analyzed for selenium
via an INAA scheme employing a 5, 15 and 25 second irradiation (φth = 8·1013 n·cm−2·s−1), decay and real-time count (77mSe,T1/2=17.4 s), respectively, using high-resolution gamma-ray spectroscopy with Westphal pulse pile-up correction. Selenium distribution
will be discussed relative to differentiated function and oxygenation of the specific tissues.
Authors:T. Nichols, J. Morris, V. Spate, C. Tharp, C. Baskett, T. Horsman, M. Mason, and T. Cheng
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.
Authors:Xue Yang, Joseph T. F. Lau, Zixin Wang, and Mason C. M. Lau
Background and aims
Masculine role discrepancy (i.e., men perceiving themselves not living up to the ideal manhood and being less masculine than the typical “man”) and related discrepancy stress were associated with some risk behaviors. No study has looked at their relationships with addictive use of social networking sites (SNSs), an emerging potential public health concern. The study constructed a moderated mediation model to test whether masculine role discrepancy would be positively associated with discrepancy stress, which would, in turn, be positively associated with addictive use of SNS, and whether self-esteem would buffer (moderate) the association between masculine role discrepancy and discrepancy stress.
A random population-based cross-sectional telephone survey interviewed 2,000 Hong Kong male adults in the general population.
Currently unmarried and non-cohabiting, younger, and better educated participants reported higher addictive use of SNS scores than others. Adjusted for these variables, masculine role discrepancy and discrepancy stress were positively associated, and self-esteem was negatively associated with addictive use of SNS scores. Path analysis indicated that masculine role discrepancy was associated with addictive use of SNS through discrepancy stress (mediation); self-esteem buffered (moderated) the association between masculine role discrepancy and discrepancy stress; self-esteem was not significantly associated with addictive use of SNS in this model with good fit.
The findings support the general strain theory’s postulation that strain is associated with stress, which is in turn associated with addictive use of SNS sites. Implications, potential interventions, and future studies are discussed in this study.
Authors:K. Mathew, S. Bürger, S. Vogt, P. Mason, M. Morales-Arteaga, and U. Narayanan
The International Organization for Standardization (ISO) Guide to the expression of Uncertainty in Measurement (GUM) was developed
to meet the demand for a standardized way of evaluating and expressing uncertainties. The Davies and Gray (D&G) titrimetry
method is routinely used in nuclear safeguards for uranium accountability measurement and a statement of the uncertainty that
can reasonably be attributed to the measured assay value is therefore of importance. A mathematical model for an uncertainty
evaluation of D&G measurements in compliance with ISO GUM is presented. This is illustrated by a numerical example and the
utilization of the uncertainty budget is explored.
Authors:Xue Yang, Dan Qiu, Mason C. M. Lau, and Joseph T. F. Lau
Background and aims
Few studies have tested the underlying mechanisms in the association between workaholism and depression. This study aims to investigate the potential mediation effects of work-life balance stress and chronic fatigue and depression among Chinese male workers in Hong Kong.
A population-based study among male workers in Hong Kong (n = 1,352) was conducted. The self-reported scales of assessing workaholism, work-life balance stress, chronic fatigue and depressive symptoms were included in the questionnaire. Path analysis was conducted to test the proposed mediation model.
Workaholism was directly and indirectly associated with depression through work-life balance stress and chronic fatigue, respectively. The association between work-life balance stress and chronic fatigue was statistically significant in the correlation analysis but not in the path analysis. As high as 30.5% of the participants were classified as having probable chronic fatigue, while 8.4% of the participants were classified as having probable depression.
Workaholism is a stressor that may induce negative consequences on well-being and health among male workers in Hong Kong. Interventions to help workers with time and stress management and fatigue reduction may be beneficial for their mental health. Theoretical and practical implications are discussed.