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  • Author or Editor: S. Banerjee x
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Abstract  

Liquid-liquid extraction of zirconium(IV) was investigated from dilute hydrochloric acid medium by salicyaldoxime (HA) in dichloromethane. The metal was spiked with 95Zr and analyzed by its radioactivity. The effects of different donors, like trioctyl phosphine oxide (TOPO), triphenyl phosphine oxide (TPPO), tributyl phosphine oxide (TBPO), tributyl phosphate (TBP), trioctyl amine (TOA) and Amberlite LA-2 were studied. The adduct formation constants for both binary species (metal-ligand) and ternary species (metal-ligand-donor) were also calculated form the distribution data.

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Endophytic fungi of three tissues (petiole, bark and leaf) of Alstonia scholaris were assessed. A total number of 1,152 endophytic fungi were isolated from 1,002 different plant segments of seven different localities of Paschim Medinipur, West Bengal, India. The isolated fungi belong to nineteen genera, including four unidentified fungi and yeast. Colletotrichum sp. (20.39%) and Sordaria sp. (29.68%) were most commonly isolated from this plant. Hyalopus sp., Fusarium sp. and Curvularia sp. were also isolated. The colonization frequency of endophytic fungi is much higher in leaves (44.66%) in comparison to petioles (32.16%) and barks (23.17%). The study provided evidence for tissue specificity of endophytic fungi. The endophytic fungal species diversity was higher in plant segments collected from Gopegarh and Khoirullahchak, while diversity was the lowest in Rice mill area. Screenings of antimicrobial activity of these isolated endophytic fungi were done. Eight endophytic fungi showed antimicrobial activity. Among them Curvularia sp., Aspergillus sp. and one unidentified fungus showed maximum activity against test pathogens.

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Abstract  

Carrier-free radionuclides of tungsten and tantalum, 176,177W and 176,177Ta have been produced by heavy ion activation of holmium target with 97 MeV 16O5+ beam. Radiochemical separation scheme has been developed to isolate tungsten and tantalum radionuclides from the holmium target matrix.

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Abstract  

Interaction of albumin with no-carrier-added metal radionuclides was studied in multielemental environment using dialysis technique. No-carrier-added 197mHg, 199–201Tl, 199–200Pb, 204Bi and 204,205Po were produced by irradiating Au target consecutively with 7Li and 12C beams. Similarly, 61Cu, 66–68Ga, 62,63Zn, 66,67,69Ge, 71,72As and 73Se were produced by irradiating cobalt target consecutively with 16O, 7Li and 12C projectiles. These no-carrier-added radionuclides were chemically separated from the bulk target before studying their interaction with albumin. It was found that Hg and Ga strongly bind with albumin, whereas Bi, Po, As, and Se do not bind at all with albumin. The binding affinities of Pb, Tl, Cu and Zn radionuclides towards albumin are moderate.

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A new zeolite derivative has been prepared by interacting Th(IV) and complexone in HCl medium and neutralising with aqueous ammonia. The amorphous and siliceous derivative showed a total mass loss of 29.25% in TG for stepwise dehydration, dehydroxylation and decomposition. Heats of reaction were 1167.6 J g−1 at 88.7°C and 75.167 J g−1 at 492.5°C for loss of volatile components and decomposition respectively.29Si and27Al MAS NMR spectra as well as XRD data of the derivative before and after calcination indicate presence of both four-coordinated and six-coordinated Al in varying ratios and the total loss of crystallinity.

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Abstract  

Cadmium(II) and Pb(II) ions replace the sodium(I) ion in commercial molecular sieve deolite. These exchanged derivatives have been interacted with adsorbates like CO2 and NH3 and the new exchanged and adsorbed derivatives characterized by their TG and IR spectral data. It is concluded that deolite can be effectively employed for removal of hazardous Cd(II) and Pb(II) ions as well as the gaseous adsorbates.

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Abstract  

This paper reports the effect of the variation of citrate to nitrate ratio on the thermal decomposition characteristics of alumina precursor and the properties of nanocrystalline alumina synthesized using this auto-ignition process. The technique involves the auto-ignition of a citrate-nitrate gel occurring between Al(NO3)3 and citric acid to yield an ash powder that upon calcination at 1373 K produced α-alumina. The auto-ignition was restricted to a particular range of citrate to nitrate ratio in the gel. The resulting powder exhibited large surface area (40–50 m2 gm−1) and fine crystallite size. It was established from various characterization techniques that the alumina powder prepared with a C/N ratio of 0.3 has got the optimum powder characteristics compared to the rest of the batches, thus establishing the importance of maintaining a stoichiometric or near stoichiometric C/N ratio. The process has a higher degree of reproducibility and a good potential for large-scale production of alumina.

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Abstract  

The effects of neutral organophosphorous compounds on the extraction of thorium by -hydroxy naphthaldoxime in xylene are reported. Enhancement of the extraction is explained by a complex adduct formation in the organic phase. Synergistic coefficients and apparent formation constant of complex adducts are calculated.

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Summary  

Nuclear quadrupole interaction study using Time Differential Perturbed Angular Correlation technique has been carried out to identify the sites where hafnium can reside in hydroxyapatite in order to mimic the behavior of plutonium adsorption on hydroxyapatite. Hf(IV) has been found to occupy three sites with the quadrupole interaction frequency(ωQ) and its asymmetry(η): (i) ωQ = 136.7(5) Mrad/s, η = 0.54(1); (ii) ωQ = 300.1(9) Mrad/s, η = 0.35(2); (iii) ωQ = 124.6(5), η = 0.0(1). Narrow frequency distributions indicate the sites are well-defined. This study has been extended to barium orthophosphate to confirm our inference for the apatite structure.

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