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  • Author or Editor: N. Ward x
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Abstract  

A prompt-gamma neutron activation technique has been developed using the (n, ) apparatus situated at the O degree through-tube of the Imperial College CONSORT II Reactor with a thermal neutron flux at the target position of approximately 2×106 n cm–2 sec–1, and a Compton-suppression system involving a lithium-drifted germanium (Ge(Li)) detector and a sodium iodide anti-Compton shield. Boron levels of 1–5 g g–1 (detection limit 0.05 g B for 10,000 sec period of measurement) can be attained using the Compton-suppression system with graphical inter-polation correction for the 472 keV sodium-ray peak contribution to the Doppler-broadened 478 keV boron gamma-ray peak resulting from the10B(n, )7Li reaction. Very good agreement is reached for boron levels compared using this system for various Standard Reference Materials and other published values. Measurement of the boron content of bone and tooth samples from rheumatoid arthritis individuals shows lower levels, (p<0.05); 16.13±7.53 g g–1, when compared with a control population; 19.79±4.18 g g–1. A positive correlation existed between the boron content of bone and tooth material for each study group. Results indicate that boron availability may be associated with rheumatoid arthritis.

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Abstract  

Brain tissue (hippocampus and cerebral cortex) from Alzheimer's disease and control individuals sampled from Eastern Canada and the United Kingdom were analyzed for Ag, Al, As, B, Br, Ca, Cd, Co, Cr, Cs, Cu, Fe, Hg, I, K, La, Mg, Mn, Mo, Ni, Rb, S, Sb, Sc, Se, Si, Sn, Sr, Ti, V and Zn. Neutron activation analysis (thermal and prompt gamma-ray) methods were used. Highly significant differences (probability less than 0.005) for both study areas were shown between Alzheimer's diesease (AD) and control (C) individuals: AD>C for Al, Br, Ca and S, and AD<C for Se, V and Zn. Aluminium content of brain tissue ranged from 3.605 to 21.738 g/g d.w. (AD) and 0.379 to 4.768, g/g d.w. (C). No statistical evidence of aluminium accumulation with age was noted. Possible zinc deficiency (specially for hippocampol tissue), was observed with zinc ranges of 31.42 to 57.91 g/g d.w. (AD) and 37.31 to 87.10 g/g d.w. (C), for Alzheimer's disease patients.

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Abstract  

In this preliminary study, scalp hair samples from 36 individuals resident in Sofia, Bulgaria, were analysed and Ag, Al, As, Au, Ba, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, F, Fe, Hg, I, K, La, Mg, Mn, Mo, Na, Ni, Rb, S, Sb, Sc, Se, Sn, Sr, Ti, V, W, and Zn were determined. Instrumental neutron activation analysis (INAA) methods were used. Three washing procedures.: distilled-deionised water; acidacetone-water; and Triton X-100 detergent-water, showed a variable elemental change strongly dependent on the procedure used. More than 18 elements (Al, As, Ba, Ca, Ce, Cl, Co, Cs, F, Fe, I, K, La, Mo, Na, Ni, Sb, Sc, Sr and V) were easily removed by water-washing. Triton X-100 detergent was more effective in removing Ag, As, Au, Cl, Cs, K, Na and Rb; but not Hg. Only S and Zn were strongly incorporated in the hair structure (less than 10% being removable by any washing technique). There is no significant age correlation with any element between the various hair treatment groups. Elevated cadmium levels were found in the hair of smokers (0.711–4.913 g/g Cd) compared with nonsmokers (0.568–2.681 g/g Cd). Comparison of the elemental data for distilled water-washed hair and studies from Oxford, England and Hastings, and Hastings, New Zealand (using the same INAA method) revealed interesting variations dependent on local industrial and nutritional factors.

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Abstract  

Thirty four elements (Al, As, Ba, Br, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Gd, Hf, Ho, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, Ti, U, V, W, Yb) were determined by instrumental neutron activation analysis in the second set of Chinese geochemical standard reference materials (sediments from GSD-9 to GSD-12, soils from GSS-1 to GSS-8, rocks from GSR-1 to GSR-6) using both thermal and epithermal irradiations. Irradiation schemes designed to utilise short, medium and long-lived nuclides were employed in order to analyse major, minor and trace elements with different half-lives. The gamma-ray spectra were measured by Ge(Li) and HP(Ge) detectors. Relevant nuclear data and possible interferences are listed, and analytical results are presented and discussed.

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Abstract  

Human placental tissue from 100 hospitalized deliveries were analysed for Ag, Al, As, Au, B, Ba, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, F, Fe, I, Hg, K, La, Mg, Mn, Mo, Na, Ni, Rb, S, Sb, Sc, Se, Sn, Sr, Ti, V, W and Zn using a combination of pre-chemical separation of sodium with hydrated antimony pentoxide and instrumental neutron activation analysis. Boron and Si values were determined using prompt gamma-ray and fast-neutron techniques respectively. Analysis of NBS-SRM Bovine Liver 1577 and a pooled standard placental tissue for 33 elements showed a good agreement with most coefficients of variation less than or equal to 15%, and recoveries of 91–104%. Symmetrical distributions, were obtained for all elemental placental values. Only Cd(–) and Zn(+) showed statistically significant correlations with birth weight, gestational age and placental weight. The influence of cigarette smoking is considered a major factor in producing elevated cadmium levels in the placental tissue of smokers and passive smokers, and hence lower birth weights.

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Abstract  

Neutron activation analysis methods incorporating thermal and prompt gamma-rays have been developed for the determination of Al, Ag, As, Au, B, Ba, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hg, I, K, La, Mg, Mn, Mo, Na, Ni, Rb, S, Sb, Sc, Se, Sn, Sr, Ti, V, W and Zn in NBS-SRM 1635 (Subbituminous) coal standard, and coals from the Barnsley-Wakefield (South Yorkshire, England) area. Precision and accuracy for multielement analysis ranged from 2,5–12.4% with good argeement with teported values for NBS-SRM 1635. Comparison is reported of the elemental values for coal from Canada, Nigeria and Bulgaria. Boron values determined by PGAA at Silwood Park, England and Listitut Laue-Langevin, Grenoble, France showed relatively good agreement.

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Abstract  

A facility for neutron capture prompt gamma-ray activation analysis, installed on a curved thermal neutron guide at the ILL High Flux Reactor, is described. Elemental sensitivities for B, Sm and Gd have been measured. The performance of the facility has been assessed by the measurement of these trace elements in eleven USGS geochemical reference samples and comparison of the results with existing values. Preliminary concentrations of B, Sm and Gd are also reported for twelve French GRS.

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