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Abstract  

The object of the present paper is to study almost pseudo symmetric manifolds admitting a type of semi-symmetric non-metric connection. Also we consider a special conformally flat almost pseudo symmetric manifold admitting a type of semi-symmetric non-metric connection.

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Conclusion  

As this brief survey has indicated, the Radiochemistry group at KSLA is deeply involved in many areas of process development. Sometimes directly, as in source or tracer application, at other times indirectly such as through activation analysis. The activities reflect the strong emphasis on process development in KSLA as a whole.

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Abstract  

The uptake of Na+, K+, Rb+, Cs+, Ag+, Ca2+, Cu2+, Sr2+, Cd2+, Ba2+, Pb2+, Sc3+, Co3+, Y3+, Sb3+, Tb3+, Zr4+ and Th4+ cations at very small concentrations has been studied over a column of stannic phosphate. The exchanger was prepared by mixing H3PO4, NaCl and SnCl4 in suitable proportions and the ratio of PSn, in the product was obtained to be 1.96. Radiochemical separations of carrier free95Zr from234Th and115mIn, from115Cd have been carried out by adopting a simple chemical procedure over a column of stannic phosphate. The -spectrum analysis showed that the separated products are of high radionuclidic purity. The separation procedures took less than half an hour with quantitative yield.

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Abstract  

Separations of tracer cations in parent daughter systems such as carrier-free210Bi from210Pb,90Y from90Sr and UX1 from U have been carried out in a column of ceric phosphate as ion exchanger. The exchanger has been prepared by mixing ceric sulfate in hot 10M orthophosphoric acid at 80°C and keeping for overnight. A pale yellow coloured precipitate was formed which was washed, dried at 70°C for 48 hours when a hard, granular variety suitable for column use, with a cerium to phosphate ratio of 1∶2 was obtained. 0.1M H3PO4 was used as medium in each of the systems studied. The β-decay curves of the separated210Bi and90Y and the γ-spectrum of UX1 show that all these activities are radiochemically pure. The separation procedures adopted in each case were very clean and simple, gave quantitative yields and took less than half an hour.

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Abstract  

Titanium phosphate as ion exchanger for column operation has been prepared by mixing TiCl4 and H3PO4 in suitable proportion. The ratio of titanium: phosphate was obtained to be 1:2.02. The uptake of Na+, K+, Rb+, Cs+, Ag+, Ca2+, Sr2+, Ba2+, Pb2+, Sc3+, Co3+, Y3+, Tb3+, Zr4+ and Th4+ cations at very small concentrations has been studied on this exchanger. The data indicated that the different cations are adsorbed in the exchanger by different mechanisms. Radiochemical separations of carrier free95Nb from95Zr, UX1 from U and45Ca from46Sc have been achieved by adopting very simple chemical procedures through a column of titanium phosphate. The -spectrum of the separated95Nb, UX1 and46Sc showed that the products are of high radionuclidic purity. The individual separation procedures took less than 20 min and the yields are quantitative.

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Abstract  

The uptake of a few polyvalent ions Ca2+ Cu2+, Zn2+, Cd2+, UO2+, Cr3+, Y3+, Ce3+, Nd3+, Sm3+, Tb3+, Tm3+, Yb3+, Lu3+, Zr4+, Hf4+, Sn4+, Nb5+, Se6+, Mo6+ and W6+ at very small concentrations has been studied over ceric tungstate exchanger. A good column variety of the material was prepared by mixing ceric sulphate in 2N H2SO4 and aqueous solution of sodium tungstate in suitable proportion. The ratio of cerium: tungstate was obtained to be 11. Separation of carrier-free95Nb from95Zr and113mIn from113Sn have been carried out by applying a very simple chemical procedure over the column of ceric tungstate. The -spectrum of separated95Nb and113mIn products were found to be of high radionuclidic purity. The separation procedure took less than 15 min and the yields were close to 100%.

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Abstract  

Since 1996, two new cases were detected in our laboratory for which the elemental concentrations derived from k 0 neutron activation analysis seem questionable. These cases concern the inconsistencies observed (1) in the concentration of Ca obtained via 47Ca and 47Sc, and (2) in the concentration of Yb obtained via the 228.5 and 396.3 keV lines of 175Yb. A recommendation is made to re-evaluate the corresponding k 0-values or true-coincidence correction factors.

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Abstract  

The reloading of research reactor Thetis (INW, Gent), in April 1996, involved the re-calibration of the irradiation facilities used for k 0-NAA. In some channels, the values of the re-measured parameters f and a significantly deviated from the ones before reloading, and the effect of this on the concentration results is demonstrated. Some additional experimental work was done in two irradiation facilities, one well-thermalized and another with a hard neutron spectrum, in order to examine the behavior of a with neutron energies up to about 60 keV. This study was performed in the context of a lasting controversy regarding the accuracy of the k 0 and Q 0 values for the 95,97Zr-isotopes, especially in view of the high 94Zr(n,g) effective resonance energy. In the irradiation channels under consideration, no evidence was found of a versus energy dependence

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Abstract  

The performance of k 0-INAA was studied for the determination of the rare earth elements (plus Th and U) in the certification of four new BCR CRM's: 667 Estuarine Sediment, 690 Calcareous Soil, 670 Aquatic Plant and 668 Mussel Tissue. Our results are critically compared with the (later on) certified values, revealing slight discrepancies for the organic matrices aquatic plant and mussel tissue. Although these discrepancies were thought to be associated with the special procedure followed for moisture content determination, no convincing explanation could be found. Mention is also made of problems that are affecting the accuracy and precision of our results, especially with respect to multiplet deconvolution or otherwise troublesome peak fitting, spectral interferences, reaction interferences (notably from 235U-fission) and the non-1/v thermal cross section behavior. Eventually, detection limits for the REEs (+ Th and U) are calculated in the four materials, allowing to evaluate the applicability of INAA to these types of bio-environmental matrices.

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Summary  

The use of a Zr-Au-Lu alloy allows the simultaneous determination of all neutron spectrum parameters relevant to the k- 0standardization of NAA, in terms of both the Høgdahl and the Westcott convention. The present paper reports on the fundamental aspects (theoretical considerations, desired composition; gamma-spectrometry protocol) of this “all-in-one” alloy and on the experimental results (radiation stability; homogeneity tests) obtained for a variety of prototypes that were produced by some firms specialized in alloying technology. It is concluded that for the most recently produced material all criteria are fulfilled to pass on to the development of a certified Zr-Au-Lu alloy, which would be quite useful not only in the practice of k- 0NAA, but for neutron spectrum monitoring in general.

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