The instrumental neutron activation analysis /INAA/ of tungsten in various steel samples has been done with a 2 Ci252Cf fission neutron source having an integrated neutron flux of 1010 ns–1 and measuring the -activity of187W on a 4 K multi-channel analyzer /MCA/ coupled to a high purity germanium /HPGe/ detector. The tungsten content of various steel samples was between 0.017 and 0.024%.
Tracer diffusion of Co2+ ions is studied in agar gel medium in the presence of some transition metal sulphates using the zone diffusion technique. A comparison between the experimental and theoretical values of diffusion coefficients computed on the basis of Onsager's theory shows a divergence between them. These deviations are explained on the basis of various effects in the iongel-water system.
Neutron activation analysis (NAA) technique has been used for the estimation of Mn, Na, and K in different varieties of oil seeds of mustard and sunflower in India. The samples were irradiated in a252Cf source with neutron flux of 109 n s–1 and the analysis was done using a multichannel analyzer (MCA) coupled to high purity germanium (HPGe) detector. Different varieties of seeds are found to have different concentrations of tracer elements when compared among themselves.
The manganese content of some industrially important steel samples viz. IS-226, spring steel, galvanized iron, high tensile steel, and mild steel is determined by instrumental neutron-activation analysis using a252Cf neutron source. The analysis is performed by measuring the activity of56Mn after /n, / reaction on a 4 k multichannel analyzer coupled to a NaI/Tl/ detector at 847 keV, as well as on a single channel analyzer on integration mode coupled to a NaI/Tl/ detector. The results obtained by both procedures show reasonably good agreement with each other.
Tracer-diffusion coefficients of Co2+ ions have been determined in 1% agar gel containing transition metal chlorides, viz. ZnCl2, NiCl2 and MnCl2 over the concentration range of 10–6–0.15 M at 25°C using the zone-diffusion technique. The results are compared with calculated values on the basis of Onsager's theory and the deviations are accounted for on the basis of various types of interactions in the ion-gel water system. Further, activation energy for the tracer-diffusion of Co2+ ions in the above mentioned electrolytes has been obtained as a function of electrolyte concentration, using measurements in the temperature range of 25–50°C. The trend in activation energy is explained on the basis of the WANG's model.
Elemental analysis of some herbal plants used in the ayurveda for curing of cardiovascular diseases has been performed using the techniques of neutron activation analysis and atomic absorption spectroscopy. The concentration of elements Mn, Na, K and Cl has been estimated by NAA using a252Cf neutron source and a high purity gemanium detector coupled to a multichannel analyzer, while the elements Ca, Cr, Co, Cu, Fe, Pb, Zn, Ni, Cd and Hg were analysed by AAS using a Perkin Elmer 3100 instrument.
The concentration dependence of experimental diffusion coefficients of managanese ions in presence of some alkali metal chlorides is examined in the light of Onsager's theory. The diffusion coefficients are measured in 1% agar gel using zone-diffusion technique. The positive and negative deviations observed at higher and lower concentrations, respectively, are explained in terms of relative contributions of various types of effects occuring in the diffusion medium. Further, the effect of supporting electrolytes on the activation energy and obstruction effect for manganese ions has been studied at 0.1M electrolyte concentration. It is observed that the magnitude of both parameters decreases in the reverse order of the charge density of alkali metal ions of the supporting electrolyte. These observations are explained by considering the distortion in the gel-water structure caused by these ions and agar molecules.
Tracer diffusion coefficients of cobalt ions have been measured in the supporting medium containing multi-electrolyte systems of alkali bromides. The electrolyte concentration was varied between 10–6-0.1M at 25°C and the diffusion coefficients were determined by zone-diffusion technique using agar gel medium. The trend in the theoretical values of diffusion coefficients is accounted for by considering the relative contribution of mobility function, ionic strength as well as ion size parameter to the theoretical value in different systems. While the deviations between theoretical and experimental values of diffusion coefficients are explained on the basis of various co-occurring effects in ion-gel-water system.
The diffusion coefficients of cobalt halides have been measured in 1% agar gel at 25°C over a wide range of concentration using the zone-diffusion technique. These values are then compared with the corresponding theoretical values computed on the basis of Onsager-Fuoss theory of diffusion. The deviations observed between the experimental and theoretical values of diffusion coefficients are explained by considering various types of interactions occurring in gel-water-electrolyte system.
The obstruction effect in the electrolyte diffusion of cobalt halides and in tracer diffusion of Co2+ ions in the presence of different supporting electrolytes at various concentrations has been studied at 25 °C using the zone diffusion technique. It has been observed that obstruction effect expressed in terms of increases with concentration and is higher for electrolyte diffusion than in tracer diffusion. Further, for a given concentration it is found to decrease with increasing charge density of an anion. These observations are explained on the basis of competitive hydration between ions and agar molecules.