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  • Author or Editor: N. Rajurkar x
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Abstract  

The activation energy for the tracer diffusion of Co2+ ions in multielectrolyte systems containing alkali bromides has been determined in agar gel medium over the temperature range of 25–45°C. The decrease in the value of the Arrhenius parameters, E and Do, with gel percentage is explained on the basis of the transition state theory. Further, studies of the influence of electrolyte concentration on activation energy and obstruction effect reveal that both parameters decrease with the former. The decrease in activation energy is explained by considering the changes in physical properties of the solution with concentration at microscopic level, while the decrease in the extent of obstruction effect is attributed to competitive hydration between ions and agar molecules in a diffusion system.

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Abstract  

The instrumental neutron activation analysis (INAA) of industrially important steel samples, viz. IS-226, IS-2002, IS-2062, SS-304, SS-310, SS-316 and of copper base alloys, viz. high brass, gun metal and copper-silver alloys is carried out with a 2 Ci252Cf neutron source. The copper and vanadium content of all the steel samples and manganese content of former three steel samples are estimated by measuring the gamma activity of66Cu,52V and56Mn radioisotopes, respectively, using a high purity germanium (HPGe) detector coupled to a 4 K multichannel analyzer (MCA). Similarly, the copper content of copper base alloys was also determined.

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Abstract  

Studies on bioaccessibility of elements were carried out by in-vitro gastrointestinal digestion simulation method combined with neutron activation analysis (NAA) using NH4HCO3 as an alternate base to commonly used base of NaHCO3. The effect of two bases namely NaHCO3 and NH4HCO3 on the bioaccessibility of the elements namely Br, Fe, K, La, Na, Rb, Sm and Zn from wheat seeds, fresh wheatgrass and commercial wheatgrass tablet was investigated. The bioaccessible concentrations of the elements were determined by neutron activation analysis (NAA). The bioaccessible concentrations of samples digested using NH4HCO3 were found to be higher by 10–15% for most of the elements than that observed using NaHCO3. In the case of fresh wheatgrass, the differences were as high as 50%. The present study indicated that NH4HCO3 can be used as a base instead of NaHCO3 in in-vitro gastrointestinal digestion simulation method.

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