[en] The effect of γ-irradiation on the plasticization of nylon 6 monofilaments with benzyl alcohol by monitoring the glass transition temperature Tg after γ-irradiation has been studied. The method applied for determining the Tg is thermomechanical. The longitudinal deformation was determined with nylon 6 monofilaments immersed in benzyl alcohol, carrying a negligible weight to keep it taut. The temperature was varied in the range 3deg - 90deg C. Samples were prepared at different irradiation doses between 0 and 16 Mrad using a Cobalt-60 source. At each irradiation dose, a percentage extension vs temperature plot was made from the data obtained, and the Tg of the irradiated filament was determined from this plot. It was observed that the Tg started increasing very slowly upto 4 Mrad. The rate is appreciably faster after 8 Mrad. At 16 Mrad the Tg rises from its value in unirradiated nylon 6 monofilaments plasticized with benzyl alcohol, that is, the control, by about 13deg C. This upward shift of Tg is an antiplasticization effect and is accompanied with change of other mechanical properties, such as extensibility and tensile strength. The paper discusses the implication of these results in terms of previously known behaviour of scission and crosslinking due to γ-irradiation in nylon 6 and explores the possibility of application of the effect in processing. (author)

[en] This paper reports on swelling studies of γ-irradiated nylon 6 films undertaken to investigate the effects of γ-irradiation in finer details. Benzyl alcohol has been used as the swelling agent. The kinetics of weight swelling of γ-irradiated nylon 6 films in benzyl alcohol was studied at different irradiation doses in the range 0 - 28.8 Mrad. It is observed that with increasing irradiation dose upto 14.4 Mrad the swelling, and hence the diffusion process are retarded; moreover, the sigmoidal nature of the percentage weight swelling vs (time)sup(1/2) plot is augmented. Above this critical dose the swelling and diffusion processes are accelerated. Besides, the sigmoidal behaviour recedes and is converted into linear behaviour at 28.8 Mrad. This behaviour indicates that a relaxation-controlled non-Fickian diffusion process is at work below 28.8 Mrad while at 28.8 Mrad a Fickian process is established. A significant effect on the equilibrium swelling in benzyl alcohol is observed. The plot of equilibrium weight swelling vs irradiation dose at 23deg C shows an initial decrease of swelling upto 3.6 Mrad at which swelling starts decreasing at accelerated rate in the dose range 3.6 - 7.6 Mrad. The rate slows down appreciably between 7.00 and 14.4 Mrad, above which there is a rapid fall. The results are correlated with scission and crosslinking processes through relative viscosity determination of formic acid solutions of the irradiated samples. It is established by combining viscosity data with kinetics and equilibrium swelling data that, besides scission, crosslinking processes are also at work in nylon 6 in the irradiation dose range 0 - 3.6 Mrad. It has been possible to bring out this point because the swelling technique seems to be preferentially sensitive towards crosslinking. (author)

[en] Formation of some enigmatic haloes (such as giant, super-giant, intermediate types, dwarf, polonium haloes etc.) has been explained, in an unified approach, on the basis of α-recoil and α-particle damage density distribution from the decay series of radon and thoron diffusing out of the highly radiation damaged inclusion and the surrounding host matrix. It is shown that the origin of these haloes can be explained without invoking the presence of any hitherto undiscovered radioelement or superheavy element in the halo inclusion. An order of magnitude estimate of the diffusion coefficient has been made. The data available in literature on different haloes have been shown to fit in well with the diffusion mechanism. (author)

[en] The fluoride ion selective electrode has been employed for an investigation of the fluoride complexes of U(IV) and Pu(IV) in 1.0 M HClO₄/NaClO₄ medium at a temperature of 25 ± 1degC. The average values of the concentration stability constants were logβ₁=8.46, logβ₂=14.64, logβ₃=19.48, and logβ₄=23.75 for U(IV) and logβ₁=7.62, logβ₂=14.75, logβ₃=20.18 and logβ₄=26.0 for Pu(IV). (author). 1 tab., 8 refs

[en] As a part of the studies on the fluoride complexing of tetravalent actinides, stability constants of Th(IV)-F complexes in 1.0 M ionic strength medium but varying H⁺ concentration were measured. The stability constant values obtained are reasonably constant when the initial acidity is varied over a range of 0.01 M to 0.9 M. The average values of the concentration stability constants are log B₁=7.62, log B₂=13.38, log B₃=17.43 and log B₄=23.19. (author)

[en] The synthesis of two ¹⁴C-labeled forms of prinomide, compounds 7 and 10, and the synthesis of a ¹⁴C-labeled form of its hydroxy metabolite are described. Compound 7 was synthesized by the reaction of phenyl isocyanate and 1-methyl-β-oxo-pyrrole-2-propanenitrile-carbonyl-¹⁴C (6), which was synthesized in three steps from 1-methylpyrrole and ¹⁴CO₂. Compound 10 was synthesized by the reaction of 8, the unlabeled form of the above ketonitrile, and ring-labeled phenyl isocyanate (9), which was synthesized in three steps from benzene-¹⁴C. The ¹⁴C-labeled form of the hydroxy metabolite 14 was synthesized by reaction of 4-methoxyphenyl isocyanate and the ¹⁴CN-labeled ketonitrile 12, followed by demethylation with boron tribromide. Labeled ketonitrile 12 was synthesized from 1-methylpyrrole, by reaction with chloroacetonitrile, followed by replacement of the chlorine atom by a ¹⁴CN group. (Author)

[en] Lower threshold energy for the revelation of nuclear tracks in a number of commonly used solid state track detectors have been measured within an accuracy of +- 50 KeV using a simple experimental technique. Measured range deficits have been correlated with the bulk etch rates and the minimum observable length of the track in the detector. It has been shown that though the tracks of very low energy particles may be registered, the inherent limitations of the revelation procedure by chemical etching and the subsequent examination under the microscope tend to increase the lower detection thresholds. The lower thresholds are quite appreciable under the etching conditions used in many of the common applications of the nuclear track detectors. (author)

[en] Stability constants of the fluoride complexes of the actinides in different oxidation states measured by potentiometric method using fluoride ion selective electrode have been presented. Procedure and precautions required to overcome certain difficulties particular to actinide ions have been discussed. Literature data from various sources have been compiled. In order to have a reasonable comparison the stability constant (β₁) values obtained in diverse ionic strength media are converted to thermodynamic stability constant, β₁⁰, using Davies equation (a modification of Debye-Huckel equation). A correlation of the β₁⁰ values with the fundamental properties of the actinide ions using various models available in the literature has been attempted. A semiempirical relation recently developed by Brown, Sylva and Ellis (BSE equation) appears to be most suitable. Using the values of ionic radii and best available values of the stability constants of a large number of metal ions from recent compilations a comparative study of the various models or relations available in the literature has been tried. For metal ions in general, the best correlation is obtained with the BSE equation. In an attempt to accommodate the unusual trend in the stability constants of the tetravalent actinides a modification in a parameter of the BSE equation has been proposed. Good agreement between the theoretically calculated and experimentally determined values for actinides in different oxidation states is then obtained in most of the cases. (author)

[en] Stability constants of the fluoride complexes of Np(IV) in 1.0M HClO₄/NaClO₄ medium at 25degC were determined using fluoride ion selective electrode. The average values of the concentration stability constant were log β₁=8.17, logβ₂=14.53, logβ₃=20.01 and logβ₄=25.95. (author). 8 refs

[en] The synthesis of ¹⁴C-labelled crotamiton, which is a fungicide, an insecticide as well as a scabicide is described. Starting from 2-bromonitrobenzene and Cu¹⁴CN, o-toluidine, labelled with ¹⁴C at the methyl group was prepared by the following sequence of reactions: NO₂-C₆H₄-Br → NO₂-C₆H₄-¹⁴CN → NO₂-C₆H₄-¹⁴COOH → NO₂-C₆H₄-¹⁴CH₂OH → NO₂-C₆H₄-¹⁴CH₂Br → NH₂-C₆H₄-¹⁴CH₃. Labelled o-toluidine was then heated with crotonic anhydride to give crotonic acid o-toluidide which was then ethylated by treatment with sodium hydride and ethyl iodide to obtain labelled crotamiton. (author)