Selective recovery of uranium from THOREX feed by hollow fibre supported liquid membrane technique containing di(2-ethylhexyl) isobutyramide (D2EHIBA) as the carrier

Hollow fibre supported liquid membrane (HFSLM) studies were carried out for the selective recovery of uranium from THOREX feed solution (0.2 g/L U+200 g/L Th+0.03 M HF+0.1 M Al(NO3)3 at 4 M HNO3) using di(2-ethylhexyl) isobutyramide (D2EHIBA) as the carrier and distilled water as the strippant. About 85% of uranium was selectively transported into the receiver phase in 30 min with <1% contamination from thorium. On the other hand, under identical conditions of feed and strip solutions, about 90% of uranium was recovered in the same time when 5% TBP (tri-n-butyl phosphate) was used as the carrier, but a relatively large amount of thorium (>10%) was also co-transported to the product side. Strip phase acidity analysis revealed significant amount of acid co-transport with both the carriers. Acid transport was found to increase with the total salt content of the feed solution. The transport of metal ions was explained with the help of a theoretical model. Stability of the liquid membrane was also studied over about 5 d for long term reusability.

Photosynthetic and fluorescence responses of Solanum melangena L. to field application of dimethoate

The organophosphorus insecticide dimethoate, at field concentration (1.419+/-0.086mga.i.g(-1)fr.wt. of leaf tissue) did not cause any significant degradation of chlorophylls and carotenoids in Solanum melangena L. On the other hand, there was significant reduction of photosynthesis, transpiration and stomatal conductance during 6h after spray application of the insecticide. Distinct change of OJIP fluorescence transient with increase of J and I rise and corresponding decrease in P rise was observed during 6h after insecticide application. The fluorescence parameters, viz., relative variable fluorescence at J level (V(j)), net rate of PS II closure (M(0)), energy dissipation (DI(0)/RC) and maximum trapping rate of active PS II (TR(0)/RC), during the same treatment period, showed significant increase but variable fluorescence (F(v)), fluorescence yield (TR(0)/Abs), electron transport probability (ET(0)/TR(0)), and activity of RC (ET(0)/RC) showed significant decrease. All physiological and fluorescence parameters, and the OJIP fluorescence transient recovered steadily to the control level during 48h after insecticide application. There was continuous reduction in the insecticide content of the leaf tissue during the observation period.

Evaluation of polymer inclusion membranes containing crown ethers for selective cesium separation from nuclear waste solution

Transport behaviour of (137)Cs from nitric acid feed was investigated using cellulose triacetate plasticized polymer inclusion membrane (PIM) containing several crown ether carriers viz. di-benzo-18-crown-6 (DB18C6), di-benzo-21-crown-7 (DB21C7) and di-tert-butylbenzo-18-crown-6 (DTBB18C6). The PIM was prepared from cellulose triacetate (CTA) with various crown ethers and plasticizers. DTBB18C6 and tri-n-butyl phosphate (TBP) were found to give higher transport rate for (137)Cs as compared to other carriers and plasticizers. Effect of crown ether concentration, nitric acid concentration, plasticizer and CTA concentration on the transport rate of Cs was also studied. The Cs selectivity with respect to various fission products obtained from an irradiated natural uranium target was found to be heavily dependent on the nature of the plasticizer. The present work shows that by choosing a proper plasticizer, one can get either good transport efficiency or selectivity. Though TBP plasticized membranes showed good transport efficiency, it displayed poor selectivities. On the other hand, an entirely opposite separation behaviour was observed with 2-nitrophenyloctylether (NPOE) plasticized membranes suggesting the possible application of the later membranes for the removal of bulk (137)Cs from the nuclear waste. The stability of the membrane was tested by carrying out transport runs for nearly 25 days.

Extraction of the uranyl ion with 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and neutral donors from dilute nitric acid medium

The extraction behaviour of Uranium (VI) from aqueous nitric acid medium employing 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) has been studied in the presence of various amides, e.g , di-2-ethylhexylacetamide (D2EHAA), di-2-ethylhexylpropanamide (D2EHPrA), di-2-ethylhexylisobutylamide (D2EHiBA) and di-2-ethylhexylpivylamide (D2EHPvA) in toluene medium. The extraction constant (log k ex) for the binary species UO2(PBI)2·nH2O was found to be 1.42±0.14 which is by far the largest amongst the corresponding values known for the other β-diketones. The overall equilibrium constant (log K) for the ternary species UO2(PBI)2·D2EHAA, UO2(PBI)2·D2EHPrA, UO2(PBI)2·D2EHiBA and UO2(PBI)2·D2EHPvA were estimated to be 6.51, 6.21, 6.11 and 5.77 respectively. This trend in equilibrium constants was in accordance with the substitution of the amides as sterically crowded amides show relatively lower equilibrium constant values. The extraction constants follow an inverse correlation with the pK a values of the β-diketonates while the equilibrium constants vary linearly with the size of the amides. The steric factors have been found to play a significant role in the co-ordination of the amides to the uranyl β-diketones when the carbonyl group is a part of the heterocyclic ring. The distribution ratios of the metal were measured in the temperature range 15 to 52 °C using each of the amide donors in combination with HPBI. Calculation of enthalpy and entropy therefrom indicated that the extraction was thermodynamically favoured process and maximum extraction resulted in the case of UO2(PBI)2·D2EHAA.

On-line anion exchange of rutherfordium in HF/HNO3 and HF solutions

The fluoride complexation of the group-4 elements Zr, Hf, and Rf, and of the pseudo-homolog Th, was previously investigated in mixed HNO3/HF solutions by studying K d values on both cation-exchange resins (CIX) and anion-exchange resins (AIX) using the automated rapid chemistry apparatus ARCA. On the CIX, the fluoride complexation of Rf was found to be weaker than that of Zr and Hf but stronger than that of Th. On the AIX, the competition for the binding sites by the counter ion NO3 - was found to be stronger for the fluoride complexes of Rf than for those of Zr and Hf. The aim of the present work is to add independent evidence to the latter result by measuring K d values for Rf on the AIX in 0.1 M HNO3/0.5 M HF and in 0.01 M HF without any HNO3. The results are obtained via an activity ratio of the long-lived α-decay descendant of 261mRf, 20-d 253Es, using the multi-column technique (MCT). These experiments corroborate the seemingly much more pronounced competition of NO3 - for the exchanging sites of the AIX with respect to [RfF x ]( x -4)- than with [ZrF x ]( x -4)- and [HfF x ]( x -4)-.

Anion-exchange behavior of Mo and W as homologs of Sg (element 106) in HCl and HNO3 as well as in mixed HCl-HF and HNO3-HF solutions

We have determined K d values for Mo and W in batch experiments on various anion-exchange resins in HCl and HNO3 as well as in mixed HCl-HF and HNO3-HF solutions in order to create a data base and to select optimum conditions for the determination of K d values of Sg (element 106) in a future on-line experiment using continuous chromatography with the multi-column technique (MCT). Their influence by hydrolysis and fluoride complexation is discussed and the average charge of the complexes is determined from slope analyses. It is shown that the selectivity of anion exchangers for the Mo- and W complexes and, thus, the separation factors between them, depend strongly on the choice of the functional group of the anion-exchange resin.

Separation of neptunium and plutonium from acidic medium using 3-phenyl-4-benzoyl-5-isoxazolone

The extraction behaviour of plutonium (IV) and neptunium (IV) was studied from nitric as well as hydrochloric acid employing 3-phenyl-4-benzoyl-5-isoxazolone (PBI) in toluene as the extractant. The forward extraction in hydrochloric acid medium was carried out in presence of several holding oxidants out of which ammonium meta vanadate was found to give the best results. The stripping behaviour of Np and Pu was studied employing a variety of reagents out of which 0.1 M hydroquinione in 1:1 HCl was the most promising. The separation of Np from Pu under simulated conditions was attempted from hydrochloric acid medium giving a decontamination factor value of >104 and ∼60% Pu recovery.

Extraction of tetravalent neptunium isoxazolonates as their TOPO adducts

The extraction behaviour of Np(IV) by 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) in the presence of tri-n-octyl phosphine oxide (TOPO) was investigated from nitric acid medium. The speciation studies, carried out by the slope analysis method, yielded binary species of the type Np(PBI)4 when only HPBI was used as the extractant and ternary species of the type Np(PBI)4·TOPO when both HPBI and TOPO were used as the extractants. The two-phase extraction constant for the binary species (log k ex) was calculated to be 10.11±0.03, while that for the ternary species was found to be 17.24±0.05. Thermodynamic parameters for the binary and ternary extraction systems were also determined. Both the binary and ternary extraction systems were found to be highly spontaneous processes with predominant enthalpy stabilization. The very high negative entropy factor suggested contribution of unfavourable steric factors.

Role of ligand basicity and stereochemistry in the extraction of plutonium(IV) isoxazolonates

The extraction behaviour of plutonium (IV) was investigated from nitric acid and perchloric acid using 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) as well as a mixture of HPBI and tri-n-octyl phosphine oxide (TOPO) in xylene. Studies on the binary extraction system Pu(IV)-HPBI indicated extraction of species of the type Pu(PBI)4. In the presence of TOPO, while species of the type Pu(PBI)3(ClO4)·(TOPO) and Pu(PBI)4·TOPO were co-extracted from perchloric acid medium, a mixture of Pu(PBI)2(NO3)2·2TOPO, Pu(PBI)3(NO3)·(TOPO) and Pu(PBI)4·TOPO were co-extracted from nitric acid medium. In addition to the electronic factors, steric factors were found to play a significant role during the formation of binary/ternary/quaternary complexes. The steric hindrance due to the unusual conformation of the isoxazolone led to lowering of the equilibrium constants for both the binary and ternary extraction systems. Possible steric factor influences are explained with the help of molecular modelling.

Evaluation of PermaNet 2.0 mosquito bednets against mosquitoes, including Anopheles minimus s.l., in India

Wash resistance and field bioefficacy of PermaNet 2.0 nets, long lasting insecticidal nets, against mosquitoes were evaluated in Assam, northeastern India. After repeated hand washings at 12-day intervals a decline in the mosquito killing ability of PermaNet nets was noted (trend chi2 38.9, p < 0.0001), yet these nets retained good insecticidal efficacy for up to 15 wash cycles, producing a 72.5% mean mortality of An. minimus 24 hours after a 3-minute exposure in World Health Organization cones after 15 washings. Significantly fewer (p < 0.001) mosquitoes were captured in self-baited landing collections in houses equipped with PermaNet nets than in houses using untreated nets in the case of culicines (p < 0.001) but not with anophelines, including An. minimus. The use of PermaNet nets resulted in noticeably fewer bites from Culex pseudovishnui (68.5%) and Cx. quinquefasciatus (70%). Blood-feeding inhibition of mosquitoes in deliberately torn PermaNet nets was seen, indicating a protective effect for those sleeping under these nets. No serious adverse effects of the PermaNet nets were reported by users.

Armigeres (Armigeres) mahantai, a new mosquito species from India

Female and male adults of Armigeres (Armigeres) mahantai, a new mosquito species, are described from Meghalaya state of northeastern India.

A novel malonamide grafted polystyrene-divinyl benzene resin for extraction, pre-concentration and separation of actinides

A new chelating polymeric extraction chromatographic resin was prepared by chemical anchoring of N,N'-dimethyl-N,N'-dibutyl malonamide (DMDBMA) with chloromethylated Merrifield resin((R)). The grafted resin exhibited stronger binding for hexavalent and tetravalent actinides such as U(VI), Th(IV) and Pu(IV) over trivalent actinides, viz. Am(III) and Pu(III). Batch studies on solid phase extraction performed over a wide range of acid solution (0.01-6M HNO(3)) revealed that ternary mixer of uranium, americium and plutonium or thorium, americium and plutonium could be separated from each other at 1M HNO(3). Desorption of U(VI), Pu(IV) and Am(III) from the loaded resin was efficiently carried out using 0.1M alpha-HIBA, 0.25M oxalic acid and 0.01M EDTA, respectively. Quantitative pre-concentration of actinide ions such as Th(IV) and U(VI) was possible from 3M HNO(3) solution. The practical utility of the grafted resin was evaluated by uranium sorption measurements in several successive cycles. The sorption efficiency of the resin with respect to uranyl ion remained unchanged even after 30 days of continuous use. The surface morphology of the resin was monitored with the help of scanning electron microscopy (SEM) technique.

Community practices of using bed nets & acceptance & prospects of scaling up insecticide treated nets in north-east India

BACKGROUND & OBJECTIVE

The National Vector Borne Disease Control Programme (NVBDCP), India has been promoting and scaling up the use of insecticide-treated nets (ITNs) in the tribal dominated malarious areas of north-east India. But, information on sleeping habits, bed net ownership and use practices, and feedback of communities in ITN--targeted areas is needed for formulating a strategic framework for upscaling the coverage of ITNs. We carried out a community-based cross-sectional survey in select areas of Nagaland and Mizoram (where ITNs were introduced) along with Assam (where ITNs were not introduced) to know the response of community.

METHODS

Following large scale introduction of ITNs during 2001-2002 in the north-eastern States of Nagaland and Mizoram by NVBDCP, India, a cross-sectional community-based survey was undertaken in April-May, 2003 covering 435 households of Nagaland and 464 households in Mizoram, using a structured questionnaire, to assess the demographic variables relevant to bed net use, bed net washing practices and acceptability of ITNs etc., for upscaling the coverage of ITNs in the surveyed communities. A total of 448 households in 8 villages in a non-ITN PHC area of Assam were served as the control area.

RESULTS

The average bet net usage per family (2.01 to 2.65). Bed net use was mostly seasonal in Nagaland where a majority (65.1-78.7%) used bed nets only during summers and monsoon as compared to the year round use in Mizoram (83.5%) and Assam (78.9%). Frequent washing of nets was most common in Assamese communities with 77 per cent households washing their nets at least once in a month. More than two third users favoured use of ITNs over the conventional indoor residual spray of DDT for malaria control.

INTERPRETATION & CONCLUSION

ITNs are widely acceptable in the user communities and a demand for ITNs is evident in the non-user communities of north-east India. Approach of treating community owned nets through an efficient service delivery mechanism will be a viable option for upscaling the ITN coverage.

Detection & molecular confirmation of a focus of Plasmodium malariae in Arunachal Pradesh, India

BACKGROUND & OBJECTIVE

During a malaria epidemiological study in Arunachal Pradesh, Plasmodium malariae like human malaria parasites were seen in blood smears from fever cases. The study was undertaken to detect the presence of P. malariae and to confirm its identity through DNA based polymerase chain reaction approach.

METHODS

Fever survey was carried out in 22 villages in Indo-Myanmar bordering district of Lohit, Arunachal Pradesh in 2005. Morphologically suspected P. malariae cases were confirmed using nested PCR based on 18S small subunit ribosomal DNA gene sequence.

RESULTS

Screening of 1,995 fever cases resulted in 9 probable cases of P. malariae based on morphological identification in Chakma tribe people residing in 2 villages. Nested PCR confirmed the identity of all probable cases of P. malariae by producing diagnostic band of 144 bp. PCR method was able to detect mixed infection of P. malariae with P. vivax and with P. falciparum.

INTERPRETATION & CONCLUSION

P. malariae may have been present in Arunachal Pradesh but most probably is being misdiagnosed due to its close resemblance with P. vivax, especially in ring forms. Estimation of actual case load of P. malariae in north-east India is, therefore, important with accurate species identification using molecular methods.