The determinations of trace elements in tissues of herons are of great interest in order to evaluate environmental contamination.
As the herons are at the top of the food chain they tend to accumulate high concentrations of contaminants in their tissues.
Besides, the effects of pollution are also severe for this species, endangering the survival and reproduction of bird populations.
In the present study, concentrations of the trace elements Br, Co, Cs, Fe, Rb, Se, and Zn were determined in livers from Great
Egret (Ardea alba) species. The liver samples were those obtained from the adult specimens found dead in the metropolitan region of São Paulo,
SP, Brazil. The liver samples were ground, freeze-dried and the elements were determined by the method of neutron activation
analysis. The elemental concentration obtained in livers of these species showed wide variations depending on the element.
Comparisons made between our results with literature data indicated that element concentrations obtained for herons from metropolitan
region of São Paulo are higher or at the same order of magnitude of those obtained for specimens from polluted areas. Comparisons
made between the results obtained for different genders of herons by applying nonparametric Mann–Whitney U test at the significance level of 0.05 indicated that female herons present Co and Se concentrations lower than those from
Nitrogen in the human body is measured in vivo using prompt neutron capture gamma-rays. The quantity of nitrogen can then be used as measured of protein. Data are presented on three groups of subjects; volunteers of different ages, those with liver ailments, and those on peritoneal dialysis. The data show that the nitrogen measurements given information (in accord with clinical findings) which is not given by indirect methods of estimating lean body mass.
The diffusion of Mn2+ ions in CoSO4 , NiSO4 and ZnSO4 containing 1% agar gel as well as that of MnSO4 in 1% agar gel was studied at 25 °C. The diffusion coefficientsat selected concentrations were determined by the zone diffusion techniqueand by measuring the concentration of diffusing ions using neutron activationanalysis.
Authors:T. Villa-Córdoba, J. López-Palacios, M. Jiménez-Reyes, and D. Tenorio
Several ornaments named tezcacuitlapilli (coccyx-mirrors) are described and chemical analyses of raw materials (slate and
pigments) were carried out by neutron activation, X-ray diffraction, scanning electron microscopy and radiography. Elemental
and statistical analyses revealed that three different kinds of slate were used in their manufacture. The white pigment contains
gypsum while ochre, yellow and red pigments contain iron oxide. These ornaments were identified as coming from the Cave of
the Sun Pyramid of Teotihuacan. An attempt was undertaken to reconstruct the contexts of their manufacture and symbolic interpretation.
Authors:T. Fukuyama, N. Kihou, H. Fujiwara, M. Nakashima, and E. Shiratani
In order to assess the effect of marine and terrestrial environmental change in the last decades on the sedimentation environment
in Ariake Bay, we collected three sediment cores. The concentrations of natural and anthropogenic radionuclides, major elements,
and rare-earth elements were measured using gamma-spectrometry and neutron activation analysis. Vertical distributions of
both radionuclides and sedimentation rates, determined using Cs-137 and Pb-210ex dating methods, varied significantly among the sites.
Authors:P. Bode, M. Bueno, K. Goraieb, and M. Koster-Ammerlaan
The Compton continuum in large sample neutron activation analysis has a measurable contribution from scattering of gamma-rays
in the sample itself besides from scattering in the detector. The continuum, therefore, contains information on the sample’s
composition, which may be made available by chemometrics. This hypothesis was tested on four types of animal fodder with similar
amounts of mineral supplements. First results indicate indisputable discrimination of the sample types if using peakless parts
of the gamma-ray spectra of the natural radioactivity of the materials as well as of those obtained after neutron activation
of 1 kg samples. It indicates that the valuable information on differences in, e.g., organic constituents may be obtained
by analyzing the Compton continuum.
Authors:R. van Sluijs, D. Bossus, J. Konings, F. De Corte, A. De Wispelaere, and A. Simonits
To account for varying dead time (frequently occurring when the measuring time is comparable with the half lives of the radionuclides in question) the use of Westphal's Loss-Free Counting technique (LFC) is preferable. However, standard gamma-ray spectrum deconvolution programs can not be applied in connection with LFC spectrometers, since this technique strongly influences the counting statistics of measured spectra. As consequence, erroneous results are likely to arise when applying peak search routines or when calculating the standard deviation of fitted peak areas or detection limits. To overcome these shortcomings, an LFC module equipped with Dual LFC Mode option should be used: this accumulates an LFC-corrected spectrum simultaneously with an uncorrected spectrum. The KAYZERO evaluation software has been modified to handle such tandem spectra.
As a result of the NBSR upgrade to 20 MW, an extensive program of recharacterization of the irradiation facilities was undertaken. These measurements were made to (1) evaluate the neutron flux density and its variability over the irradiation volume, and (2) help establish safe irradiation conditions for samples in the NBSR. Techniques used to measure the following parameters are described: thermal neutron flux density; flux variations within an irradiation volume and between irradiations; relative fast neutron flux density; maximum temperatures generated by different sample matrices in various irradiation facilities; and pressures generated in sealed containers by radiolytic decomposition.
Neutron activation analysis using low-flux isotopic neutron sources is put to use in addressing areas of applied interest in managing the Savannah River Site. Some of the applications are unique due the site's operating history and its chemical processing facilities. Because sensitivity needs for many of the applications are not severe, they can be accomplished using a 6 mg 252Cf neutron activation analysis facility. Overviews of the facility and several example applications are presented.