Characterization of novel thorium tolerant Ochrobactrum intermedium AM7 in consort with assessing its EPS-Thorium binding.

Currently, radioactive waste is disposed primarily by burial in a deep geological repository. Microorganisms thriving in such contaminated environment show tolerance to radionuclides. In the present study the bacterial flora, from soil sample collected from an area around atomic power station exposed to radionuclides and heavy metals, was cultivated and assessed for thorium (Th) tolerance. Of all the isolates, strain AM7 identified as O. intermedium was selected since it could thrive at high levels of Th (1000 mg L-1). AM7 was characterized physico-chemically and its culture medium was optimized using central composite design of response surface methodology for assessing its growth properties in presence of Th. The strain also showed exceptional exopolysaccharide (EPS) production and its yield was further analyzed using one factor study to investigate the influence of each medium component. On supplementing the EPS medium with Th, no significant decrease in yield was observed. FTIR spectroscopy revealed the functional groups of EPS involved in EPS-Th binding. To the best of our knowledge, this is the first report showing exceptional Th-tolerance by any bacteria. Such study will help other researchers to strategize an environment-friendly way of radwaste disposal.

Preclinical Combination Studies of an FGFR2 Targeted Thorium-227 Conjugate and the ATR Inhibitor BAY 1895344.

PURPOSE: Fibroblast growth factor receptor 2 (FGFR2) has been previously reported to be overexpressed in several types of cancer, whereas the expression in normal tissue is considered to be moderate to low. Thus, FGFR2 is regarded as an attractive tumor antigen for targeted alpha therapy. This study reports the evaluation of an FGFR2-targeted thorium-227 conjugate (FGFR2-TTC, BAY 2304058) comprising an anti-FGFR2 antibody, a chelator moiety covalently conjugated to the antibody, and the alpha particle-emitting radionuclide thorium-227. FGFR2-TTC was assessed as a monotherapy and in combination with the DNA damage response inhibitor ATRi BAY 1895344. METHODS AND MATERIALS: The in vitro cytotoxicity and mechanism of action were evaluated by determining cell viability, the DNA damage response marker γH2A.X, and cell cycle analyses. The in vivo efficacy was determined using human tumor xenograft models in nude mice. RESULTS: In vitro mechanistic assays demonstrated upregulation of γH2A.X and induction of cell cycle arrest in several FGFR2-expressing cancer cell lines after treatment with FGFR2-TTC. In vivo, FGFR2-TTC significantly inhibited tumor growth at a dose of 500 kBq/kg in the xenograft models NCI-H716, SNU-16, and MFM-223. By combining FGFR2-TTC with the ATR inhibitor BAY 1895344, an increased potency was observed in vitro, as were elevated levels of γH2A.X and inhibition of FGFR2-TTC-mediated cell cycle arrest. In the MFM-223 tumor xenograft model, combination of the ATRi BAY 1895344 with FGFR2-TTC resulted in significant tumor growth inhibition at doses at which the single agents had no effect. CONCLUSIONS: The data provide a mechanism-based rationale for combining the FGFR2-TTC with the ATRi BAY 1895344 as a new therapeutic approach for treatment of FGFR2-positive tumors from different cancer indications.

A Neuro-Comparative Study between Single/Successive Thorium Dose Intoxication and Alginate Treatment.

The adult male albino rats were grouped into five groups (control group and four variably treated groups with thorium (Th) in single or successive with or without alginate treatment). The IP administration of thorium nitrate (13.6 mg/kg b.wt.) induced a regional distribution and accumulation ordered as cerebellum > cerebral cortex > brain stem > hippocampus > hypothalamus > striatum. Also, it induces a significant increase in Na+, Ca2+, and Fe3+ ion content and malondialdehyde (MDA) level while K+ ions and glutathione (GSH) level were significantly decreased. On the other hand, the daily oral administration of 5% alginate showed a significant decreasing in the accumulation of thorium in the different brain areas and mitigated its hazardous effects. By the alginate treatment, Na+, Ca2+, Fe3+, and level of MDA were declined while K+ ions and GSH level showed a significant increase. The improvement of the investigated parameters was attributed to the specific chelating, regeneration, and antioxidant properties of the alginate. So, alginate administration could ameliorate the hazardous effects of thorium nitrate.

A Thorium Chalcogenolate Series Generated by Atom Insertion into Thorium-Carbon Bonds.

A new thorium monoalkyl complex, Th(CH2SiMe3)(L3) (L = MeC(NiPr)2) (2), undergoes insertion of chalcogen atoms resulting in a series of thorium chalcogenolate complexes, Th(ECH2SiMe3)(L3) (E = S, SS, Se, Te; 5-8). Complex 6 represents the first alkyl disulfide thorium species and illustrates the ability of 2 to undergo controllable, stoichiometric atom insertion. All complexes have been characterized by 1H and 13C NMR spectroscopy, FTIR, EA, and melting point, and in the case of 1, 2, and 4-8, X-ray crystallography. Insertion was achieved by balancing the thermodynamic driving force of chalcogenolate formation versus the BDE of the pnictogen-chalcogen bond in the transfer reagent. Utilizing Me3NO as an oxygen atom transfer reagent led to C-H activation and SiMe4 extrusion rather than oxygen atom insertion, resulting in the alkoxide complex Th(OCH2NMe2)(L3) (4).

Development of separation technology for the removal of radium-223 from targeted thorium conjugate formulations. Part I: purification of decayed thorium-227 on cation exchange columns.

Targeted thorium conjugates (TTCs) are being explored as a potential future platform for specific tumor targeting pharmaceuticals. In TTCs, the alpha emitting radionuclide thorium-227 (227Th) with a half-life of 18.697 d is labeled to targeting moieties, such as monoclonal antibodies (mAbs). The amount of daughter nuclide radium-223 (223Ra, t1/2 = 11.435 d) will increase during manufacture and distribution, and so a technology for purification is required to assure an acceptable level of 223Ra is administrated to the patient. Since 223Ra is the only progeny of 227Th with a long half-life (days), the progenies of 223Ra will have a very limited stay in the formulation once 223Ra is removed. The focus in this study has, therefore, been on the removal of 223Ra. In this study, the sorption and separation of 223Ra (radium(II)) and 227Th (thorium(IV)) on cation exchange columns has been evaluated as a purification method of decayed 227Th (i.e. prior to radiolabelling of a mAb and formation of TTC). The goal is to minimize the sorption of 227Th and maximize the sorption of 223Ra. Statistical experimental design with formulation and process parameters, including buffered formulations comprising citrate and acetate, at various concentrations and pH, presence of free radical scavenger and chelator, and resin amount have been evaluated for impact on the purification process. The studies have been interpreted by the aid of multivariate data analysis. The correlations between design of experimental variables and sorption are summarized by regression models. The predictive accuracy of radionuclide sorption was given by standard deviation and 95% confidence intervals originating from statistical cross validation. Experimental results and statistical models for citrate-buffered formulations verified reproducible and acceptable sorption levels of 223Ra and 227Th under selected conditions. For acetate-buffered formulations, prediction of 227Th sorption was influenced by complex variable relationships and hence a risk of obtaining irreproducibility. Fine-tuned variable levels showed, however, variable combinations predicting high sorption of 223Ra (>90%) and low sorption of 227Th (<3%) also for the acetate-buffered formulations. The optimal separation conditions should be decided based on tuning the variables levels for 223Ra in the citrate-buffered formulations, while for acetate, the optimal separation should be based on tuning variable levels for 227Th sorption. The ionic strength of the formulation also seemed to affect the radionuclide sorption. Labeling of an antibody-chelator conjugate with purified 227Th (i.e. preparation of TTC) was successful in the selected citrate-buffered formulations tested.

Comparative adsorption of Eu(III) and Am(III) on TPD.

Comparative adsorption behaviors of Eu(III) and Am(III) on thorium phosphate diphosphate (TPD), i.e., Th4(PO4)4P2O7, have been studied using a batch approach and surface complexation model (SCM) in this study. The results showed that Eu(III) and Am(III) adsorption increased to a large extent with the increase in TPD dose. Strong pH-dependence was observed in both Eu(III) and Am(III) adsorption processes, suggesting that inner-sphere complexes (ISCs) were possibly responsible for the adsorption of Eu(III) and Am(III). Meanwhile, the adsorption of Eu(III) and Am(III) decreased to a different extent with the increase in ion strength, which was possibly related to outer-sphere complexes and/or ion exchange. In the presence of fulvic acid (FA), the adsorption of Eu(III) and Am(III) showed high enhancement mainly due to the ternary surface complexes of TPD-FA-Eu(3+) and TPD-FA-Am(3+). The SCM showed that one ion exchange (≡S3Am/Eu) and two ISCs (≡(XO)2Am/EuNO3 and ≡(YO)2Am/EuNO3) seemed more reasonable to quantitatively describe the adsorption edges of both Eu(III) and Am(III). Our findings obviously showed that Eu(III) could be a good analogue to study actinide behaviors in practical terms. However, it should be kept in mind that there are still obvious differences between the characteristics of Eu(III) and Am(III) in some special cases, for instance, the complex ability with organic matter and adsorption affinity to a solid surface.

Thorium induced cytoproliferative effect in human liver cell HepG2: role of insulin-like growth factor 1 receptor and downstream signaling.

Thorium-232 ((232)Th), a naturally-occurring actinide has gained significant attention due to its immense potential as a nuclear fuel for advanced reactors. Understanding the biological effects of (232)Th would significantly impact its efficient utilization with adequate health protection. Humans administered with (232)Th (thorotrast patients) or experimental animal models showed that liver is one of the major sites of (232)Th accumulation. Present study reports cellular effects of (232)Th-nitrate in a human-derived liver cell (HepG2). Results showed that the low concentration of (232)Th (0.1-10 µM) induced proliferation of HepG2 cells which was inhibited by the pre-treatment of cells with neutralizing antibody against insulin-like growth factor 1 receptor (IGF-1R). Consistently, (232)Th treatment was found to increase the phosphorylated level of IGF-1R-associated molecule, IRS1 which serves to activate PI3K and MAPK signaling pathways. Pre-treatment with specific inhibitors of PI3K (LY294002) or JNK-MAPK (SP600125) significantly abrogated the cytoproliferative effect of (232)Th. Immunofluorescence analysis showed increased levels of phospho-Akt and phospho-JNK, downstream kinases of IGF-1R, in (232)Th-treated HepG2 cells suggesting the role of IGF-1R-mediated signaling in (232)Th-stimulated cell proliferation. The cell cycle analysis showed that (232)Th increased S and G2-M cell fractions concomitant to the increase of cyclin-E level. Thus, the present investigation highlights the role of IGF-1R-mediated signaling in the cytoproliferative effect of (232)Th in human liver cells at low concentration.

The role of chemical interactions between thorium, cerium, and lanthanum in lymphocyte toxicity.

Thorium, cerium, and lanthanum are metals present in several types of minerals, the most common of which is monazite. Cerium and lanthanum are elements in the lanthanides series. Thorium, an actinide metal, is a hazardous element due to its radioactive characteristics. There is a lack of information describing the possible chemical interactions among these elements and the effects they may have on humans. Toxicological analyses were performed using cell viability, cell death, and DNA damage assays. Chemical interactions were evaluated based on the Loewe additivity model. The results indicate that thorium and cerium individually have no toxic effects on lymphocytes. However, thorium associated with lanthanum increases the toxicity of this element, thereby reducing the viability of lymphocytes at low concentrations of metals in the mixture.

Evaluation of electrospray ionisation mass spectrometry as a technique for the investigation of competitive interactions: a case study of the ternary Th-Mn-EDTA system.

RATIONALE: Electrospray ionisation mass spectrometry (ESI-MS) is a useful tool for exploring the speciation of solution-phase metal complexes; however, the quantification of ternary systems is challenging due to the differences in the electrospray response of different species. Here, the Th-Mn-EDTA system was investigated to evaluate the capability of ESI-MS for quantifying the species present. METHODS: Increasingly complex mixtures of Th(IV), Mn(II) and EDTA were analysed using manual flow injection of samples into an HPLC grade water mobile phase delivered to an ion trap mass spectrometer fitted with an ESI interface (ThermoQuest Finnigan Mat LCQ). Mass spectra were obtained in the positive and negative ion modes over a mass-to-charge (m/z) range from 50-2000. RESULTS: The instrumental response to EDTA was affected by the addition of Th(NO(3))(4) but not MnCl(2), while the response to both Th-EDTA and Mn-EDTA species was affected by addition of the other metal salt. Internal standards were also found to suppress signals to different extents. Therefore, each signal suppression was carefully quantified as the solution became more complex, and signal correction factors were used in conjunction with regular external calibration. Mixed metal signals were quantified adequately. CONCLUSIONS: This study showed the complexity of quantifying a ternary system involving different co-existing species. Nonetheless, the step-wise protocol developed provided quantitative data on the displacement of Mn from its EDTA complex by Th.

Synthesis, spectral, thermal and antibacterial investigations of mixed ligand complexes of thorium(IV) derived from 8-hydroxyquinoline and some amino acids.

Mixed ligand Th(IV) complexes of the type [M(Q)(L)(NO3)2] x 2 H2O have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and N- and/or O- donor amino acids (HL) such as L-lysine, L-aspartic acid and L-cysteine as secondary ligands. The metal complexes have been characterized on the basis of elemental analysis, electrical conductance, room temperature magnetic susceptibility measurements,spectral and thermal studies. The electrical conductance studies of the complexes in DMF in 10(-3) M concentration indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intra-ligand and charge transfer transitions, respectively. Bonding of the metal ion through N- and O- donor atoms of the ligands revealed by IR studies and the chemical environment of the protons is also confirmed by NMR studies. The thermal analysis data of the complexes indicate the presence of crystallized water molecules. The agar cup and tube dilution method have been used to study the antibacterial activity of the complexes against the pathogenic bacteria S. aureus, C. diphtheriae, S. typhi and E. coli.

Synthesis, characterization and antibacterial studies on some mixed ligand thorium complexes with N- and O-donor ligands.

Mixed ligand Th(IV) complexes of the type [M(Q)(L)(NO3)2] x 2H2O have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and N- and/or O- donor amino acids (HL) such as L-threonine, L-tryptophan and L-isoleucine as secondary ligands. The metal complexes have been characterized on the basis of elemental analysis, electrical conductance, room temperature magnetic susceptibility measurements, spectral and thermal studies. The electrical conductance studies of the complexes in DMF in 10(-3). M concentration indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intra-ligand and charge transfer transitions, respectively. Bonding of the metal ion through N- and O-donor atoms of the ligands revealed by IR studies and the chemical environment of the protons is also confirmed by NMR studies. The thermal analysis data of the complexes indicate the presence of crystalline water molecules. The tube dilution method has been used to study the antibacterial activity of the complexes against the pathogenic bacteria S. aureus, C. diphtheriae, S. typhi and E. coli.

Actinide sulfides in the gas phase: experimental and theoretical studies of the thermochemistry of AnS (An = Ac, Th, Pa, U, Np, Pu, Am and Cm).

The gas-phase thermochemistry of actinide monosulfides, AnS, was investigated experimentally and theoretically. Fourier transform ion cyclotron resonance mass spectrometry was employed to study the reactivity of An(+) and AnO(+) (An = Th, Pa, U, Np, Pu, Am and Cm) with CS(2) and COS, as well as the reactivity of the produced AnS(+) with oxidants (COS, CO(2), CH(2)O and NO). From these experiments, An(+)-S bond dissociation energies could be bracketed. Density functional theory studies of the energetics of neutral and monocationic AnS (An = Ac, Th, Pa, U, Np, Pu, Am and Cm) provided values for bond dissociation energies and ionization energies; the computed energetics of neutral and monocationic AnO were also obtained for comparison. The theoretical data, together with comparisons with known An(+)-O bond dissociation energies and M(+)-S and M(+)-O dissociation energies for the early transition metals, allowed for the refining of the An(+)-S bond dissociation energy ranges obtained from experiment. Examination of the reactivity of AnS(+) with dienes, coupled to comparisons with reactivities of the AnO(+) analogues, systematic considerations and the theoretical results, allowed for the estimation of the ionization energies of the AnS; the bond dissociation energies of neutral AnS were consequently derived. Estimates for the case of AcS were also made, based on correlations of the data for the other An and the electronic energetics of neutral and ionic An. The nature of the bonding in the elementary molecular actinide chalcogenides (oxides and sulfides) is discussed, based on both the experimental data and the computed electronic structures. DFT calculations of ionization energies for the actinide atoms and the diatomic sulfides and oxides are relatively reliable, but the calculation of bond dissociation energies is not uniformly satisfactory, either with DFT or CCSD(T). A key conclusion from both the experimental and theoretical results is that the 5f electrons do not substantially participate in actinide-sulfur bonding. We emphasize that actinides form strikingly strong bonds with both oxygen and sulfur.

Studies of the spin-Hamiltonian parameters and defect structures for Gd3+ ions in zircon-structure silicates MSiO4 (M=Zr, Hf, Th).

The spin-Hamiltonian parameters (g factors g∥, g⊥ and zero-field splittings b2(0), b4(0), b4(4), b6(0), b6(4)) for 4f7 ion Gd3+ at the tetragonal M4+ site of zircon-structure silicates MSiO4 (M=Zr, Hf, Th) are calculated from a diagonalization (of energy matrix) method. The Hamiltonian concerning this energy matrix contains the free-ion, crystal-field interaction and Zeeman interaction terms and the 56×56 energy matrix is constructed by considering the ground multiplet 8S7/2 and the excited multiplets 6L7/2 (L=P, D, F, G, H, I). The defect structures of Gd3+ centers in the three MSiO4 crystals are yielded from the calculation. The results are discussed.

EPR evidence for the restricted mobility of NO2 in gamma irradiated thorium nitrate pentahydrate Th(NO3)4·5H2O.

Electron paramagnetic resonance (EPR) studies were conducted on gamma irradiated polycrystalline sample of thorium nitrate pentahydrate, Th(NO(3))(4)·5H(2)O, in the temperature range of 100-300 K. The most prominent species with triplet hyperfine structure in the EPR spectrum was identified as NO(2). The EPR spectrum gave evidence for the stabilization of NO(2) in at least three different sites slightly differing in spin Hamiltonian parameters (Site(1): g(x)=2.0042, g(y)=1.9911, g(z)=2.0020, A(x)=54.20 G, A(y)=48.50 G and A(z)=65.25 G; Site(2): g(x)=2.0042, g(y)=1.9911, g(z)=2.0020, A(x)=54.20 G, A(y)=48.50 G and A(z)=67.85 G; Site(3): g(x)=2.0045, g(y)=1.9911, g(z)=2.0015, A(x)=54.20 G, A(y)=49.05 G and A(z)=72.45 G). The EPR spectra for Site(1) revealed molecular dynamics of NO(2) from a slow motion region to fast motion region as the sample temperature was varied from 100 to 300 K. This led to a change in EPR spectrum from orthorhombic to axial, indicating preferred rotation of NO(2) molecule about the O-O bond direction. However, the NO(2) molecule at Site(2) was found to be rigid throughout the entire temperature range. The differences in the mobility of NO(2) molecules occupying the two sites could be attributed to the fact that in one case NO(2) was bonded to thorium or water and in the other case it was weakly bound. The NO(2) bound to thorium through two oxygen atoms or bound to thorium on one side through one oxygen atom and hydrogen bonded to water on the other side remains rigid throughout the entire temperature range, while NO(2) situated at interstitial sites or adsorbed on the surface exhibits mobility with increase in temperature above 100K.

Solid thoron source preparation in a porous mineral matrix.

Thoron and progeny are decay products of (232)Th with a great impact on human health. The release of thoron gas from the mining and milling of thorite, monazite and other major thorium ores has been recognised as a potential radiological health hazard. For precise measurements, calibration is a very important factor. This paper describes a cheap and easy way of producing a stable thoron source made of thorium nitrate packed in a porous clay mineral matrix used as (220)Rn generator. The source should have a small spherical shape and be fired at 600°C; this will lead to a great pore volume, necessary for the thoron gas. High importance should be given to the water uptake. The exhalation power of (220)Rn was measured using a Lucas scintillation cell. Experimental efficiency values obtained ranged between 0.16 and 1.44 %.

Comparison of thorium(IV) and uranium(VI) carboxyphosphonates.

The hydrothermal reactions of thorium nitrate and uranyl acetate with carboxyphenylphosphonic acid and HF result in the formation of ThF(2)(PO(3)C(6)H(4)CO(2)H) and UO(2)(PO(3)HC(6)H(4)CO(2)H)(2).2H(2)O, respectively. ThF(2)(PO(3)C(6)H(4)CO(2)H) adopts a pillared structure constructed from thorium oxyfluoride layers built from [ThO(4)F(4)] units that are bridged by carboxyphenylphosphonate to yield a three-dimensional network. UO(2)(PO(3)HC(6)H(4)CO(2)H)(2).2H(2)O forms one-dimensional chains of UO(6) tetragonal bipyramids that are bridged by the phosphonate moiety of the ligand. The carboxylate portion of the structure links the chains together into layers via a hydrogen-bonding network. The higher effective charge and more isotropic coordination of the Th(IV) centers versus the uranium centers contained within uranyl cations allow for coordination by the protonated carboxylate portions of the ligands to the thorium cations, which does not occur with uranium in carboxyphosphonates. UO(2)(PO(3)HC(6)H(4)CO(2)H)(2).2H(2)O displays vibronically coupled fluorescence and the potential for energy transfer from the ligand to the charge-transfer bands of the uranyl cations. The main fluorescence by the ligand is quenched in ThF(2)(PO(3)C(6)H(4)CO(2)H).

Removal of lead (II) from aqueous environment by a fibrous ion exchanger: polycinnamamide thorium (IV) phosphate.

The objective of the present research was to synthesize, characterize and to investigate the removal efficiency of lead (II) ion from synthetic lead solution by a hybrid fibrous ion exchanger. In the present study polycinnamamide thorium (IV) phosphate was synthesized by co-precipitation method and was characterized using SEM, XRD, FTIR and TGA-DSC. To know the practical applicability, a detailed removal study of lead ion was carried out using the material. The removal of lead was 81.2% under optimum conditions. Adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R(2) (correlation coefficient) >0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin-Radushkevich isotherm.

Thorium-induced neurobehavioural and neurochemical alterations in Swiss mice.

PURPOSE: Thorium ((232)Th), a heavy metal radionuclide that targets the liver and skeleton, has been shown to accumulate in the central nervous system at low levels. The present study was aimed to investigate neurobehavioural and neurochemical changes in mice treated with (232)Th at sub-lethal doses. MATERIALS AND METHODS: Swiss albino mice were administered intraperitoneally with thorium nitrate. The chelation-based therapeutic effect of calcium diethylenetriamine pentaacetate (Ca-DTPA) was tested on the (232)Th-treated mice. (232)Th localisation was determined in brain regions by the Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) method. Achetylcholine esterase (AChE) activity in different brain regions was evaluated to assess the cholinergic function of mice CNS. Oxidative damage was evaluated by assessing the activities of antioxidant enzymes (i.e., superoxide dismutase and catalase) and the level of lipid peroxidation. The neurobehavioural alteration in the treated mice was studied by the shuttle box method. RESULTS: (232)Th accumulation found in different brain regions followed the order: Cerebellum (Cbl) > cortex (Ctx) > hippocampus (Hp) > striatum (Str). However, removal of (232)Th by Ca-DTPA was significant from brain regions like Cbl, Ctx and Str but not from Hp. A significant increase in lipid peroxidation and acetylcholine esterase (AChE) activity was observed in the treated mice but activities of superoxide dismutase and catalase was found substantially decreased. (232)Th treatment impaired the learning and memory-based neurobehaviour of the mice. Furthermore, our data suggest that Ca-DTPA injection in (232)Th-treated animals failed to improve the neurobehaviour of the treated mice, perhaps because Ca-DTPA could not decorporate (232)Th or mitigate (232)Th-mediated neurochemical changes effectively from/in hippocampus, a brain region implicated in learning and memory response. CONCLUSION: Administration of (232)Th in mice caused neurobehavioural alteration and impairment of cholinergic function, which might be the consequence(s) of oxidative stress induction in different brain regions.

Polyacrylamide thorium (IV) phosphate as an important lead selective fibrous ion exchanger: synthesis, characterization and removal study.

The objective of the present research was to synthesize, characterize and to investigate the removal efficiency of lead (II) ion from synthetic lead solution by a hybrid fibrous ion exchanger. In the present study polyacrylamide thorium (IV) phosphate was synthesized by co-precipitation method and was characterized using SEM, XRD, FTIR and TGA-DSC. To know the practical applicability, a detailed removal study of lead ion was carried out. The removal of lead was 52.9% under neutral condition, and using 0.4 g of adsorbent in 100 mL of lead solution having initial concentration of 100 mg/L. Adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R(2) (correlation coefficient)>0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin-Radushkevich isotherm. The percentage removal was found to increase gradually with increase in pH and 99% removal was achieved at pH 10. The process was rapid and equilibrium was established within first 30 min.

Determination of the specific alpha activity of thick sources with a large area ZnS(Ag) scintillation detector.

A method for determining the specific alpha activity of thick sources using a large area ZnS(Ag) scintillation detector is presented. In this method a quadratic relationship between the detector response and window thickness is assumed. This method provides a quick estimation of alpha activity in the sample, so it is an indicative method. The aim of this experimental work is to approve theoretical assumption and to develop a standard routine method for absolute alpha measurements of thick contaminated environmental sources. For this purpose reference material U(3)O(8) and spiked standards of soil were used. Measurements of contaminated soil samples from south Serbia showed the practical application of this method.