Application of k0-method in instrumental neutron activation analysis to glass matrix: test study for low power research reactor GHARR-1

In this work k₀-INAA (via IAEAk₀-software) has been applied on glass samples to determine major, minor and trace element concentration. As many as 50 elements were detected and quantified with 3–5 mg of 0.1 % AuAl comparator monitor (0.1 % gold–99.9 %Alumimum wire). The average concentration of SiO₂, Na₂O, CaO, Al₂O₃ and MgO ranged between 76–96 %, 11.15–12.66 %, 5.26–10.71 %, 1.13–2.73 % and 3.51–6.23 % respectively. The relative concentrations of impurity elements; Cr, Fe, Mn and Co determined from the glass samples were used to match the physical appearance (color) of the glass based on general knowledge of colored glass production. The analytical procedure was validated using SRM 610 (glass matrix) and SRM GBW07106 (rock matrix) both as control samples which indicated a relative uncertainty of 15 and 6 % respectively for SRM 610 and SRM GBW07106. The relative sensitivity at which some of the elements were detected in major, minor and trace levels have indicated, that the k₀-method in instrumental neutron activation analysis using low power research reactor is a useful technique in glass analysis and could equally be used for forensic and archeological glass characterization.     

Application of instrumental neutron activation analysis to plant medicines in Ghana: A review

Some essential elements in eleven plant medicines used at the Center for Scientific Research into Plant Medicine (CSRPM), Mampong-Akwapim, Ghana, for the management and cure of various diseases were determined by instrumental neutron activation analysis (INAA), using thermal neutrons at a flux of 5^.10¹¹ n^.s^-1.cm^-2. The plant medicines were: Sirappac powder-E, Tina-A powder, Blighia powder, Aphrodisiac powder, Ninga powder and Lippia tea. The others are Olax powder, Ritchiea powder, Momordica powder, Kenken and Fefe powder. Concentrations of seventeen elements namely Al, Br, Ca, Cl, Co, Cu, Cr, K, Mn, Mg, Na, Rb, Sb, Sc, Ta, V, and Zn have been determined by short, medium and long irradiation times. Of these elements Co, Sb, and Sc are found to be present at the trace level, Br, Cu, Cr, Mn, Rb, Ta, V and Zn at the minor level, while Al, Ca, Cl, K, Mg and Na were generally at major level. The differences in the concentration of the elements are attributed mainly to soil composition and climate in which the plants grow. Standard reference material NIST SRM-1571 (Orchard Leaf) was analyzed simultaneously with the samples. The precision and accuracy of the method were evaluated using real samples and the standard reference material. It was found that the elemental concentrations measured in the NIST SRM-1571 were within ±10% of the reported values. The importance of these elements as related to human health and nutrition has been discussed.     

Simultaneous determination of tantalum,niobium, thorium and uranium in placer columbite-tantalite deposits from the Akim Oda District of Ghana by epithermal instrumental neutron activation analysis

Summary Tantalum, niobium, thorium and uranium contents of 21 columbite-tantalite minerals from the Akim Oda District of Ghana have been determined using epithermal instrumental neutron activation analysis (ENAA) with a conventional counting system. As thermal neutron filters, boron carbide was encapsulated in the irradiation vials during irradiation. The samples were irradiated at one of the outer irradiation channels in the Ghana Research Reactor-1 facility, and counted directly. Various elements were identified and quantified using 172 keV of ^182mTa, 871 keV of ^94mNb, 86.5 keV of ²³³ Th and 74.7 keV of ²³⁹U. The precision and accuracy of the method were evaluated using standard reference materials and the precision was found to be within 5% with comparable accuracy. The composition of columbite-tantalite minerals ranged from 33.1% to 59.2% Ta₂O₅ and 19.2% to 44.6% Nb₂O₅, ThO₂ and U₃O₈ the levels were 0.024-0.045% and 0.014-0.048%, respectively.     

Optimization of spectral sensitivities of mosaic five-band camera for estimating chromophore densities from skin images including shading and surface reflections

Optical Review - In this paper, the spectral sensitivities of a mosaic five-band camera were optimized using a numerical skin phantom to perform the separation of chromophore densities, shading and...     

A comparative study of AutoDock and PMF scoring performances,and SAR of 2-substituted pyrazolotriazolopyrimidines and 4-substituted pyrazolopyrimidines as potent xanthine oxidase inhibitors

4-Alkylidenehydrazino-1H-pyrazolo[3,4-d]pyrimidines, 4-arylmethylidenehydrazino-1H-pyrazolo[3,4-d]pyrimidines, and 2-substituted 7H-pyrazolo[4,3-e]-1,2,4-triazolo-[1,5-c]-pyrimidines as potential xanthine oxidase inhibitors were docked into the active site of the bovine milk xanthine dehydrogenase using two scoring functions involved in AutoDock 3.05 and the CAChe 6.1.10. The correlation coefficiency obtained between the AutoDock binding energy and IC₅₀ of the inhibitors was better than that obtained by the CAChe-PMF docking score. Many ligands exhibited one to four hydrogen bonds within the active site, where the detected hydrogen bonds by CAChe was identified quantitatively in the docked conformation by using MOPAC 2002. These ligands were docked into a long, narrow channel of the enzyme leading to the molybdopterin active moiety, with hydrogen bonding and electrostatic interaction between the planar aromatic moiety of the ligand and the enzyme. Furthermore, SAR among inhibitors was investigated, which revealed that the oxo group of pyrazolopyrimidine analogs is essential for its activity and the tricyclic derivatives are shown to be more potent than bicyclic ones. The mode of interaction of the docked inhibitors was described in details.     

The impact of small-scale mining activities on the levels of mercury in the environment: The case of Prestea and its environs

To obtain the baseline information of mercury pollution due to gold mining activities in Prestea and its environs total mercury (T-Hg) concentrations were measured in water and stream sediment. The samples were analyzed by instrumental neutron activation analysis (INAA). They were irradiated and counted without any preconcentration. Higher levels of T-Hg concentration were found in samples at the sites with extensive small-scale galamsey gold mining activities than at the sites with low small-scale galamsey activities. Concentrations varied between 6.80–19.82 mg/l for water and 28.90–84.30 mg/kg in sediment at sites with extensive small-scale mining activities. At low small-scale mining sites concentration levels for T-Hg varied between 0.50–9.10 mg/l and 1.20–22.75 mg/kg in water and sediment, respectively. The concentration levels of T-Hg in water from all the sampling sites are in excess of the WHO tolerable limit of 0.001 mg/l for drinking water.Some financial support for the work from the National Nuclear Research Institute is highly appreciated. The authors thank Messers Nick Opata and Ekow Quagraine, the technicians at the NAA laboratory for their contribution during preparation, irradiation and counting of samples. We also thank the team of reactor operators.     

Application of NAA standardization methods using a low power research reactor

Two widely used neutron activation analysis (NAA) standardization methods (relative and k ₀) have been validated at the Ghana Research Reactor-1 (GHARR-1) Centre using environmental and biological standard reference materials (SRMs). The samples were IAEA Soil-7 as an environmental sample, and NIST Orchard Leaves 1571 as a biological sample. The qualitative and quantitative analyses were done using a high resolution Canberra N-type high purity germanium (HPGe) detector. The accuracy and precision were evaluated for the elements analysed. The concentrations of most of the elements were found to be within 10% of the certified values. Precision was calculated from six replicate measurements and was found to be within 15%.