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  • Author or Editor: M. Hyvönen-Dabek x
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Abstract  

Proton-induced prompt gamma-ray emission (PIGE) analysis has been used for the determination of light elements in human dense bone samples. Li, B, N, O, F, Na, Mg, Al, P and Ca peaks were detected. Smoothed, freeze-dried samples were irradiated in vacuo by 2.4 MeV protons and the induced prompt gamma rays recorded with a 110 cm3 Ge(Li) detector. Absolute concentrations were calculated on the basis of both calibration standards and pure element gamma-ray yields. The mean (±1 S. D.) concentrations as ppm or weight % obtained for 15 dense bone samples were: B 8.0 (3.3)ppm, N 12.2 (0.8)%, O 34.8 (2.3)%, F 639 (417)ppm, Na 5763 (371)ppm, Mg 2078 (290)ppm, P 9.26 (0.50)% and Ca 20.4 (1.3)%. The detection limits obtained without any prior concentration of the bone samples were: 0.3 ppm for Li, 2.0 ppm for B, 1.0% for N, 1.0% for O, 1.0 ppm for F, 3.0 ppm for Na, 50 ppm for Mg, 22 ppm for Al, 600 ppm for P and 0.8% for Ca. Detection limits for other light elements (4≤Z≤21) have also been estimated.

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Abstract  

A simple proton beam (PIXE) arrangement developed for a low energy accelerator was used for the determination of absolute concentrations of nine trace elements in human bone samples. The 2.4 MeV proton beam was externalized through a thin (2 μm) aluminiummylar foil. Using an air cooling system, the foil withstood a high current (0.5–1 μA) for a long time. The samples were cooled to prevent damage and volatilization of elements. The induced X-rays were detected with a Si(Li) detector and the external beam was monitored with a second detector, measuring K X-rays induced in atmospheric argon. The mean (SD) trace element levels (ppm) measured in dense bone by comparison with hydroxyapatite/standard mixtures were: Cr<2.0, Mn<2.3, Fe 7.58 (1.55), Ni<2.4, Cu 3.58 (2.16), Zn 144 (27), Pb 12.2 (2.5), Br 12.4 (5.5) and Sr 47.7 (14.3). The detection limits for these elements achieved in this work were about 1 ppm when rather short measuring times (∼10 min) were used. The coefficient of variation of a single measurement, e.g. for Zn, was 3–4%. Because of the slow turnover of dense bone, such measurements provide a means of monitoring long term trace element exposure.

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Abstract  

Cross-section values for 14.7 MeV neutrons have been measured for the following reactions:

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\begin{gathered} ^{24} Mg(n,p)^{24} Na - (187 \pm 7)mb;^{25} Mg(n,p)^{25} Na - (74 \pm 9)mb; \hfill \\ ^{26} Mg(n,\alpha )^{23} Ne - (55 \pm 6)mb;^{35} Cl(n,p)^{37} S - (22 \pm 3)mb; \hfill \\ ^{35} Cl(n,2n)^{34m} Cl - (9.3 \pm 1.5)mb;^{86} Sr(n,p)^{86m} Rb - (14 \pm 2)mb; \hfill \\ ^{88} Sr(n,p)^{88} Rb - (19 \pm 3)mb;^{86} Sr(n,2n)^{85m} Sr - (244 \pm 32)mb; \hfill \\ ^{88} Sr(n,2n)^{87m} Sr - (289 \pm 33)mb. \hfill \\ \end{gathered}$$ \end{document}
An analysis of available cross-section data for these reactions has been performed and preferred mean values for each reaction are given.

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Abstract  

Proton-induced gamma-ray emission (PIGE) analysis has been applied to the determination of total nitrogen concentration of blood sera from hospital patients. Both the reaction14N(p,p )14N,E = =2313 keV, and the reaction15N(p, )12C,E =4439 keV, have been used. From 37 patients, the range of the nitrogen concentrations obtained was 9.54–16.3 g/l with a mean of 12.0 g/l. The corresponding total protein concentrations varied between 59 and 96 g/l, measured in a clinical laboratory autoanalyser using the biuret method. The range of the albumin concentrations was 29–46 g/l. The nitrogen concentrations correlated well with the total protein concentrations (r=0.802). The multiple correlation of nitrogen versus (albumin+(total protein-albumin)) gives a coefficient of 0.175 for albumin and 0.161 for total protein-albumin. The results agree with expectations and support the potential usefulness of the rapid PIGE method for medical studies.

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