The Level of Selenium and Some Other Trace Elements in Different Libyan Arable Soils Using Instrumental Neutron Activation Analysis

Elemental analysis of soils from two different arable regions in Libya was carried out to measure the level of many trace elements. Instrumental neutron activation analysis was used for the determination of 10 elements, viz., (Ba, Ce, Co, Cr, Cs, Fe, Sc, Se, Th, and Zn), using their long-lived radionuclides. The accuracy of the measurements has been evaluated by analyzing two IAEA soil reference materials: IAEA Soil-7 and IAEA leak sediment SL-1; precision has been estimated by triplicate analysis of the sample and that of the reference material. Irradiations were carried out at the Tajura Research Center reactor, at 5-MW power level. It is clear that in the Libyan soil selenium concentration is somewhat lower than in other countries. The results show that trace metal concentrations in Libyan clay surface soil are higher than the sandy soil.     

Nuclear corrosion monitoring—

Nuclear corrosion technique has been developed for the assay of various heavy metals released through corrosion and abrasion into electrolytes from various biomaterials like amalgams, chromium— cobalt and gold alloys, steel, and titanium. Application of the technique in measurement of selective release rates under static or dynamic conditions, i.e., during cyclic loading, is discussed. The elements chromium, cobalt, copper, gold, iron, mercury, molybdenum, silver, titanium, and zinc have been quantitatively assessed. In vivo corrosion measurements are further included. By combining the present nuclear tracer technique with ESCA technique, knowledge about reaction mechanisms occurring at the interface solid/liquid is obtained. Exposure of humans to various heavy metals from biomaterials, e.g., dental materials, can be estimated using the NCM technique. The technique also has a potential for selective release measurements of several nuclides possessing suitable radioanalytical properties from other types of alloys immersed in various liquid environments.     

Effects of reactor temperature and sample mass on the activation of biological and geological materials with a SLOWPOKE reactor

Neutron activation analysis with a SLOWPOKE reactor relies on the stability of the neutron flux in the irradiation sites. Flux monitors were irradiated to measure the flux variation with the reactor temperature and with the amount of moderator in the irradiation vial. The thermal flux decreased by 2.7% for a 10‡C increase in reactor temperature. The thermal flux increased by up to 8% and the fast flux decreased by up to 13% depending on sample size and hydrogen content.     

海藻中有机碘的研究Ⅰ.海藻中有机碘含量测定

采用国际上目前通用的差减法来计算海藻中的有机碘,即首先测定海藻中的总碘和无机碘,其差减值为有机碘.碘的测定采用了碘离子选择电极法和中子活化法作为对照。在此基础上,还测定了新鲜海带中碘的含量、分布以及有机碘和无机碘的比例。研究结果表明,海带中碘的平均含量占鲜重的0.133％,其中88％的碘是以碘离子的形式存在,有机碘只占总碘的12％,同时海带不同部位碘的含量不同,叶部外缘含碘较多,是叶中部的2倍左右,尤其叶尖部的含量达到鲜重的0.183％。而有机碘的含量分布规律则不同,有机碘的含量在靠近根部的位置较高,为鲜重的13.9％。这种分布特点可能与海带的生命活动规律有关。     

Determination of multielement concentrations in normal human organs from the Japanese

In order to elucidate the distribution of elements in organs from healthy Japanese, instrumental neutron activation analysis (INAA), based on the preliminary examination, was applied to quantitative determination of multielements in nine organs autopsied (brain, heart, kidney, liver, lung, muscle, pancreas, spleen, and thyroid). The following results were obtained: (1) The values obtained for each element could be considered to be representative as "normal values" and "ranges" in organs from healthy Japanese males; (2) the essential elements Br, Cl, Co, Cu, Fe, K, Mn, Na, Rb, Se, and Zn were not affected by external environmental factors or by racial difference; (3) renal and hepatic Cd levels were very high in several cases and the accumulation has still been in progress in the Japanese, whereas the contaminant elements are low in each organ except for lung.     

In Vitro Distribution of Gold in Serum Proteins after Incubation of Sodium Aurothiomalate and Auranofin with Human Blood and its Pharmacological Significance

This study presents a comparative drug–protein, in vitro, binding profile of sodium aurothiomalate and auranofin. It was found that about 40% of total protein-bound gold is attached to albumin after incubation of aurothiomalate with whole blood for 24 h and about 29% of it was with α₁-globulin and the least amount was found with γ-globulin (6.1%). On the other hand, approximately 84% of the protein-bound auranofin gold attached to globulins of which 51% was found with β-globulin band. It was almost equally distributed among albumin, α₂-globulin and γ-globulin, and showed least affinity for α₁-globulin. The gold analyses were performed by standardless instrumental neutron activation method duly validated by use of an established atomic absorption method. The results of this study explain to some extent the difference in, in vivo, pharmacokinetics and pharmacodynamics of the two drugs.     

Experience on the neutron activation of natural/enriched Re,Sm, and Ho nuclides in a reactor for the production of radiotherapeutic radionuclides

In recent years, much effort has been concentrated on the use of Β-emitting radionuclides for the treatment of various cancers. The reports suggested the application of¹⁸⁶Re and¹⁵³Sm as radiotherapeutic radionuclides for the treatment of palliative widespread skeletal métastases, whereas¹⁶⁶Ho was suggested as an agent for radiation synovectomy. Hence, a study on the production of¹⁸⁶Re,¹⁵³Sm, and¹⁶⁶Ho radionuclides was carried out by neutron activation of the appropriate target materials using a Pakistan Atomic Research Reactor (PARR-1) at a neutrons flux of 1 x 10⁴ n/cm² s. These radionuclides were then converted to appropriate radiopharmaceuticals for their use on animals and patients. The targets of natural Re (metal), natural Sm₂O₃, enriched Sm₂O₃ (99.06%), Sm(NO₃)₃ (solid), Sm(NO₃)₃ (liquid), and Ho₂O₃ were irradiated in the PARR-1. After irradiation, the purity of these radionuclides were checked by a multichannel analyzer, Canberra series 85 (MCA) coupled with HPGe detector and then measured in radioisotope calibrator Capintec ionization chamber model CRC-5RH. The effect of the irradiation time and amount of target material was investigated on the production yields of the radionuclides. The results showed an increase in the specific activity of Re with an increase in the irradiation time from 1 to 72 h, whereas a decrease in the specific activity was observed with increase in the amount of Re from 10 to 100 mg. Similar results were obtained for¹⁵³Sm and¹⁶⁶Ho radionuclides. The results further indicated that the specific activity of powder target was much less than the liquid targets for¹⁵³Sm. Their conversion to the appropriate radiotherapeutic radiopharmaceuticals were also carried out by investigating the experimental conditions and acceptable quality of¹⁸⁶Re-HEDP and¹⁵³Sm-EDTMP complexes were prepared. These complexes were then used on animals and patients which showed good performance.     

Trace elements in rock salt and their bioavailability estimated from solubility in acid

In this study, 18 partly commercially available samples of rock salt from Austria, Germany, Pakistan, Poland, Switzerland, and Ukraine were investigated with respect to their content of trace elements using instrumental neutron activation analysis. Elements detected were Al, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, La, Mn, Na, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, and Zn, some of them only in individual cases. An estimation of the bioavailability of these trace elements was performed by dissolving an equivalent of the sodium chloride samples in diluted hydrochloric acid (simulating stomach acid), filtering off the insoluble components, and analyzing the evaporated filtrate. It could be shown that in most cases bioactive trace elements like Fe can be found in rock salt in the form of almost insoluble compounds and are therefore not significantly bioavailable, whereas thorium, for example, was partly bioavailable in two cases. A significant contribution to the recommended daily intake of metal trace elements by using rock salt for nutrition can be excluded.     

Determinations of subnanomole elemental levels by NAA and their possible impact on human health related issues

Neutron activation analysis (NAA) is an appropriate tool for the determination of trace elements in biological systems. The virtually blank-free NAA procedures fittingly complement precautions employed in sampling and sample preparation of biological matrices. Results from instrumental NAA procedures used to establish baseline values and time trends for elements in human tissues demonstrate the advantages as well as the limits of these procedures for nanomole and, in a considerable number of instances, subnanomole elemental levels. In addition, subnanomole mass fractions have been determined with extremely low limits of detection by employing NAA with radiochemical separations isolating very low levels of radioactivity from the matrix background. The elements reviewed in this article include Cr, Se, Pt, and others that have been determined by NAA at subnanomole levels in human tissues and body fluids and in biological macromolecules.     

Noninvasive techniques for measuring body elemental composition

In the past 20 yr, in vivo analysis of body elements by neutron activation has become an important tool in medical research. In particular, it provides a much needed means to make quantitative assessments of body composition of human beings in vivo. The data are useful both for basic physiological understanding and for diagnosis and management of a variety of diseases and disorders. This paper traces the development of the in vivo neutron activation technique from basic systems to the present state of the art facilities. A scan of some of the numerous clinical applications that have been made with this technique reveals the broad potentialities of in vivo neutron activation. The paper also considers alternative routes of future development and raises some of the questions now faced in making the technique more widely available to both medical practitioners and medical investigtors. In vivo neutron activation has opened a new era of both clinical diagnosis and therapy evaluation, and investigation into the modeling of body composition. The techniques are new, but it is already clear that considerable strides can be made in increasing accuracy and precision, increasing the number of elements susceptible to measurement, and reducing the dose required for the measurement.     

Evaluation of trace elements in lung samples from coal miners using neutron activation analysis

In this study, instrumental neutron activation analysis was applied to the determination of Sc, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Th, and U in lung samples from miners working in coal mines located in the state of Santa Catarina, Brazil. These results were compared to those from a control group constituted of healthy individuals. The results showed that the elements determined exhibit considerable intersubject variability within a single group of individuals and the mean values of concentrations in miners’ lungs were higher than those of normal individuals. Lung samples presented U concentrations varying from 11 to 890 Μg/kg. Therefore, for some samples, the contribution of the uranium fission products in the analysis of La, Ce, Nd, and Sm was considered by determining the interference correction factors. The accuracy of the results was evaluated by analyzing certified reference materials.     

Iron and Other Metals in Neuromelanin, Substantia Nigra, and Putamen of Human Brain

Abstract: Radiochemical neutron activation analysis has been used to determine the concentration of 36 elements in neuromelanin, 22 elements in substantia nigra, and 32 elements in putamen of healthy subjects without signs of neurological disorders. Substantia nigra and putamen tissues were carefully dissected from the brain using special surgical instruments and tools as well as an adequate sampling procedure to avoid the risk of metal contamination during sampling. Neuromelanin was isolated from putamen by a multiple-step procedure (extraction with phosphate buffer, lipid and protein elimination by methanol extraction, and sodium dodecyl sulfate-proteinase). The isolated pigment as well as substantia nigra and putamen underwent neutron activation analysis involving irradiation in a high-neutron-flux reactor, radiochemical separations, and counting of the induced radionuclides by computer-based γ-ray spectrometry. Iron was the element present in the highest concentration in all analyzed samples. The amount of iron was similar in substantia nigra and putamen (3,000 and 3,830 ng/mg wet weight, respectively) and 10 times higher in neuromelanin (30,800 ng/mg dry weight). Zinc was also present at high levels in three samples, ranging from 16.8 (substantia nigra) to 1,500 ng/mg (neuromelanin). Elements such as Zn, Cr, Se, Sr, Co, Sb, Ni, Hg, Ce, Au, Ag, Ta, and Sc were present in neuromelanin at much higher concentrations than in substantia nigra and putamen. These findings indicate that substantia nigra and putamen contain metals at higher concentrations than observed in blood and that neuromelanin has a particular affinity for metals.     

An evaluation of thermal and epithermal neutron activation analysis compton suppression methods for biological reference materials

For neutron activation analysis (NAA), the usual matrix problems of sodium, chlorine, and bromine are well known to give rise to high backgrounds that inhibit the determination of several trace elements for short-lived or medium-lived NAA. For long counting times in long-lived NAA, very low backgrounds are required to achieve good sensitivities. We have investigated the use of thermal and epithermal NAA in conjunction with Compton suppression to determine several elements such as arsenic, antimony, cadmium, and mercury, at the level of a few nanograms. The values of these techniques are discussed in contrast to the standard radiochemical methods.     

Trends in trace element determinations in blood,serum, and urine of the dutch population,and the role of neutron activation analysis

A critical review on the quality of literature data on trace elements in human blood, serum, and urine of inhabitants in the Netherlands has shown that many of the currently available data have been established 15–20 years ago. Only in a few publications are quality indicators mentioned, which should be considered typical—and minimal —for studies resulting at reference values. The use of neutron activation analysis for determination of trace elements in human body fluids was restricted to a few studies in the 1970s. However, although it is frequently assumed that the sensitivity of NAA might be insufficient, it is demonstrated that modern, large, well-type Ge detectors may serve well for the determination of trace elements in human body fluids via radiochemical NAA, for example.     

Comparative analysis of two dynamic mechanistic models of beef cattle growth

The INRA Growth Model (IGM) and the Davis Growth Model (DGM) are two dynamic mechanistic models developed to predict protein and fat deposition in growing cattle whatever the production system. Both models depend on animal genotype and age, metabolizable energy intake (MEI) and knowledge of previous growth. The aim of this paper was (i) to identify in which situations DGM and/or IGM provide reliable estimations of body protein and fat, (ii) to give insight on the improvements needed in each model and (iii) to discuss the usefulness of comparative analysis for improvement of mechanistic models. We performed a comparative analysis of DGM and IGM with three datasets from published experiments on Salers heifers, Angus-Hereford steers and Charolais bulls. Each model was fitted independently to each dataset. Both models gave accurate and precise predictions of body protein. They also performed well for body fat in Charolais bulls growing continuously. However, DGM tended to underestimate body fat deposition during feeding restriction periods with Salers heifers. This suggests that DGM overestimated heat production during periods of low MEI. IGM was not sensitive enough to MEI as it overestimates body fat at low MEI and it underestimates body fat at high MEI in Angus-Hereford steers. Presently, IGM does not take into account metabolizable energy concentration (MEC) of the diet and thus does not simulate different growth trajectories for same MEI but different MEC. These results suggest that model's structure and equations for protein accretion in DGM and IGM are valid. Future improvements will focus on prediction of heat production during feed restriction periods for DGM and on mathematical formulation of feed energy utilisation for fat synthesis in IGM in order to improve model sensitivity to MEI. Comparative analysis provides meaningful information on the models behaviour for further improvement of processes simulations.     

Noninvasive measurement of aluminium in human bone: Preliminary human study and improved system performance

Aluminium has been measured in the hands of 18 referent subjects and six aluminium welders using the technique of in vivo neutron activation analysis. The minimal detection limit (MDL) in the human subjects was 28.0 μgAl/gCa, whereas it was 19.5 μgAl/gCa in calibration standards. On average the aluminium exposed subjects had higher levels of aluminium in their hands than did the referent subjects. However, this difference only just achieved significance at the 5% level and should be treated with caution, since the study had not been deliberately designed to assess this difference. Following the preliminary human study, improvements were made to the measurement system with respect to the gamma-ray detector array and to the timing sequence of irradiation-transfer-counting. These improvements were tested on the calibration standards, lowering the MDL from 19.5 μgAl/gCa to 8.32 μgAl/gCa. A similar improvement in human measurements would result in an in vivo MDL of 12.0 μgAl/gCa.     

The influence of light quality on C4 photosynthesis under steady-state conditions in Zea mays and Miscanthus×giganteus: changes in rates of photosynthesis but not the efficiency of the CO2 concentrating mechanism

Differences in light quality penetration within a leaf and absorption by the photosystems alter rates of CO₂ assimilation in C₃ plants. It is also expected that light quality will have a profound impact on C₄ photosynthesis due to disrupted coordination of the C₄ and C₃ cycles. To test this hypothesis, we measured leaf gas exchange, ¹³CO₂ discrimination (Δ¹³C), photosynthetic metabolite pools and Rubisco activation state in Zea mays and Miscanthus × giganteus under steady‐state red, green, blue and white light. Photosynthetic rates, quantum yield of CO₂ assimilation, and maximum phosphoenolpyruvate carboxylase activity were significantly lower under blue light than white, red and green light in both species. However, similar leakiness under all light treatments suggests the C₄ and C₃ cycles were coordinated to maintain the photosynthetic efficiency. Measurements of photosynthetic metabolite pools also suggest coordination of C₄ and C₃ cycles across light treatments. The energy limitation under blue light affected both C₄ and C₃ cycles, as we observed a reduction in C₄ pumping of CO₂ into bundle‐sheath cells and a limitation in the conversion of C₃ metabolite phosphoglycerate to triose phosphate. Overall, light quality affects rates of CO₂ assimilation, but not the efficiency of CO₂ concentrating mechanism.