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  • Author or Editor: A. Garg x
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Abstract  

Radiation induced decomposition of solid alkali metal nitrates at room temperature has been studied up to an absorbed dose of 300 kGy. [NO 2 ] increases with absorbed dose. From the kinetic scheme
\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} $$NO_3^ - \xrightarrow{{{}^k1}}NO_2^ - + 0; O + NO_2^ - \xrightarrow{{{}^k2}}NO_3^ - ;$$ \end{document}
and
\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} $$O + NO_3^ - \xrightarrow{{{}^k3}}NO_2^ - + O_2$$ \end{document}
, rate constants have been evaluated for the overall radiolytic decomposition of alkali metal nitrates. This kinetic scheme is applicable in the low dose range. At higher doses, however, the radiation induced reaction, NO 2 +1/2 O2 NO 3 may also contribute. The overall rate constants are 0.13×10–6 (LiNO3), 1.05×10–6 (NaNO3), 10.10×10–6 (KNO3), 9.50×10–6 (RbNO3) and 25.50×10–6 (CsNO3) kGy–1.
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Abstract  

A radiochemical solvent extraction method has been developed for the simultaneous determination of submicrogram amounts of Cd and Hg using115mCd and203Hg tracers respectively and thionalide as a single complexing reagent. Hg was determined by 0.05% thionalide in ethyl methyl ketone (EMK) at pH 8.5, masking Cd with 0.1M KCN. From the aqueous phase Cd was demasked using formal-dehyde-acetic acid, pH adjusted to 9.5 and extracted into 0.05% thionalide in chloroform. The method is simple, fast and yields accurate results.

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Abstract  

Knowledge of occurrence and concentration of trace elements in dust particulates from and around industrial establishments is essential to know the source of pollutants and atmosphere quality. Dust particulates from two cement factories in the central part of India were analyzed for 5 minor (Cl, Fe, K, Mg, Na) and 23 trace elements (Ag, As, Ba, Br, Cd, Co, Cr, Cs, Dy, Eu, Ga, Hf, Hg, La, Mn, Sb, Sc, Se, Sm, Sr, Th, W and Zn) by INAA and RNAA techniques. Significant differences have been observed for some toxic trace elements at different locations. Mn content is particularly high in all the dust particulates. Urban particulate (SRM 1648) and Coal fly ash (SRM 1633a) from NIST and Pond sediment (CRM No. 2) from NIES were also analyzed. The data have been analyzed and interpreted in terms of air quality at different locations inside the plant and two factories.

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Abstract  

Gamma-radiolytic decomposition of zirconium nitrate and its binary mixtures with potassium halides viz. KCl, KBr and KI has been studied at different compositions up to an absorbed dose of 550 kGy. Radiolytic decomposition has been found to decrease with the absorbed dose. It also varies with the concentration of zirconium nitrate in the binary mixtures. G(NO 2 ) values are enhanced by the addition of halides but only at 75% composition. It is not affected so significantly by KI. A plot of G(NO 2 ) vs. composition of the binary mixtures of the nitrates shows a somewhat parabolic curve with a minimum at 75% Zr(NO3)4+25% KX composition. A part of the energy absorbed by the system is being taken up by the halides depending upon their nature and concentration. Thermal decomposition shows slow decomposition, finally yielding an oxynitrate of indefinite composition.

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Abstract  

Instrumental Neutron Activation Analysis /INAA/ has been employed for the determination of 15 major, minor and trace elements in human and animal blood samples. Dry whole blood samples along with NBS and IAEA standards were irradiated for 5 min, 1 h, 5 h and 10 h with reactor thermal neutrons and counted using high resolution -spectrometry at successive intervals. Data for a new IAEA proposed CRM Mixed Human Diet /H-9/ is reported.

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Abstract  

Gamma — radiolytic decomposition of sodium and potassium nitrates and its admixtures with respective cyanide and borate additives has been studied over a wide absorbed dose range from 675 to 500 kGy. The decomposition of nitrate increases with the nature and concentration of the additive in the admixture. The enhancement is more significant at >80 mol% of the additive.G(NO 2 ) values, calculated on the basis of electron fraction of the nitrate salt, decrease with increasing concentration of the nitrate. ESR spectral studies suggest the formation of radical species such as BO4 and BO 3 2− etc, in borates whereas in case of cyanide additive FH centres are produced. The radical species and colour centres so produced may then transfer their energy to nitrate and cause enhancement in decomposition. A comparison with other oxyanion additives shows thatG(NO 2 ) values decrease in the order PO 4 3− >B4O 7 2− >SO 4 2− >CO 3 2− . Similarly, the nature of the cation also affects the decomposition.

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