The influence of micelles, formed by the aggregation of nonionic surfactant molecules, on positronium formation (combination
of e− and e+) probability is discussed in the light of radiation chemical phenomenon at the end part of the radiation track. The contribution
due to the parapositronium/narrow-component intensity in the presence of micellar aggregation and further structural reorganization
constitutes important aspects of the ortho-para conversion process.
A simple solvent extraction procedure for an effective separation of traces of tantalum from rock phosphate samples has been
developed and used in its determination through neutron activation analysis. The tantalum contents in the samples were found
to be about 3.10−7%.
Studies on the distribution of various oxidation states of recoil sulphur formed by35Cl(n, p)35S reaction in the alkali halides, namely, NaCl, KCl and RbCl have been made. A suitable anion exchange method using Amberlite
IRA-410 in the chloride form has been described for rapid separation of the various radiosulphur species. The elution was
carried out by means of nitrate solutions. The observed results on the effect of cation environment in affecting the distribution
of radioactive sulphur amongst its various oxidation states were discussed on the basis of electron affinity and ionic size
of the metal ion in question.
A number of samples of sodium phosphate glasses doped with Cd/Co or Ag chlorides were prepared and characterized by X-ray
diffraction, IR spectral, ion transport and DSC studies. It was found from DSC studies that the glass transition temperature
(Tg) and crystallization temperature (Tc) values increased with the increasing concentrations of the dopants Cd or Co chlorides. However, the Tg and Tc values were found to decrease when the AgCl was taken as the dopant and the following sequence is observed: Tg(CoCl2)>Tg(CdCl2)>Tg(AgCl); Tc(CoCl2)>Tc(CdCl2)>Tc(AgCl) These results have been discussed and explained on the basis of changes in the structure of sodium phosphate glassy
matrix by the addition of different cations as dopants.
A number of samples of sodium and silver phosphate glasses doped with various compositions of some transition metals viz. iron, manganese and zinc chlorides alongwith undoped samples of sodium and silver phosphate glasses were synthesized and characterized by X-ray diffraction, IR spectral, electrical conductivity and differential scanning calorimetry (DSC). The glass transition temperature (Tg) and crystallization temperature (Tc) values obtained from DSC curves were found to increase with increasing concentration of the dopant Fe/Mn/Zn chlorides in both sodium and silver phosphate glasses and the following sequence is observed:
The increase in Tg and Tc values indicate enhanced chemical durability of the doped glasses. The electrical conductivity values and the results of FTIR spectral studies have been correlated with the structural changes in the glass matrix by the addition of different transition metal cations as dopants.
Hafnium ion forms a strong complex with nitrilotriacetic acid (NTA). But there is a controversy about the nature of the complex on whether it is a 1:1 or a 1:2 complex. We have carried out an electrophoresis experiment and supplemented data to establish the nature of the complex. Our data indicates that it is a 1:2 complex i.e. [Hf(NTA)2]2- in which the coordination number 8 has been satisfied for hafnium.
Complexes of Hf with polyaminopolycarboxylic acids viz. diethylene-triamine-penta-acetic acid (DTPA) and its dimethoxy derivative DMDTPA have been studied using paper chromatography at different acidities. Kinetic stabilities of the complexes have also been looked at. Behaviors of these two ligands in complexing with Hf(IV) have been found to be similar. The extent of complexation reduces slowly with acidity and increase with time and reaches a maximum around 70-80% after about 24 hours.
A method for the separation of carrier-free arsenic from bulk amount of germanium has been developed.74,73As has been produced through the reactionnatGe(p,xn)47,73As with 13 MeV protons obtained from Variable Energy Cyclotron, Calcutta. The separation is performed by the distillation
of Ge followed by anion exchange separation of As(V) using Dowex 1×8 anion exchange resin. The overall chemical yield is found
to be (87±3%).