Browsing by Author "Nguyen, CD"

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    Polymeric titanium oxychloride sorbent for 188W/188Re nuclide pair separation
    (Taylor & Francis, 2009-01) Le, VS; Nguyen, CD; Pellegrini, PA; Bui, VC
    The chemical synthesis conditions (TiCl4: iPrOH reagent ratio and reaction temperature scheme) were optimized for the preparation of polymeric titanium oxychloride sorbent which met the requirements for clinically useful 188W/188Re generator production, such as high W-adsorption capacity, high 188Re-elution yield, low 188W-breakthrough, and good mechanical stability. This polymeric material was formed by polycondensation of titanium-oxychloride units, the chemical formula of which was supposed as [OTiO (Ti40 Cl80 (OH) 80 (TiO2)95.60H2O) OTiO]n. The effect of the W-content of tungstate solution on the WO42- ion adsorption (with minimizing the poly-tungstate ion adsorption) and its covalent bonding with the Ti metal atoms in the polymeric matrix were justified with respect to the optimal W-adsorption conditions for the preparation of a useful 188W/188Re generator column. The high W-adsorption capacity of about 515.6 mg W/g sorbent and 188Re elution yield of higher than 85% wereachieved. The large difference in the distribution ratio values found for alumina and polymeric titanium oxychloride sorbent in 0.005% NaCl solution (DW,Re-188 = 50 and DW, Re-188 = 1.0, respectively) offered an advantage for the preparation of a consecutive-elution based 188Re generator system which combined both 188Re elution and 188Re concentrating processes in one portable system. This generator system is of a tandem column type which consists of a polymeric titanium oxychloride sorbent coupled to an alumina column. This system gave a 188Re concentration factor of approximately 10. The overall 188Re yield achieved from this system was >80%. 188W isotope and elemental tungsten breakthrough were not detected in its 188Re eluate. This system thus offers a potential application for clinically useful 188Re production using low specific radioactivity 188W (around 500 mCi/g) producible in a medium neutron flux reactor. © 2009, Taylor & Francis Ltd.
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    Preparation of inorganic polymer sorbents and their application in radionuclide generator technology
    (International Atomic Energy Agency, 2009-07-01) Le, VS; Nguyen, CD; Bui, VC; Vo, CH
    Absorbents based on poly zirconium compound (PZC) and poly titanium compound (PTC) were synthesized for the preparation of 188W/188Re generators. The chemical composition, molecular structure and physicochemical characteristics of these adsorbents were investigated. The adsorption properties of PZC and PTC sorbents in different tungstate solutions and the elution performance were investigated. Tungsten adsorption capacities of about 520 mg of tungsten per gram of PZC and 515 mg of tungsten per gram of PTC and a 188Re elution yield greater than 80% for both PZC and PTC sorbents were achieved. A 188Re eluate concentration process was developed by eluting 188Re from the tandem system of 188W-PTC-alumina columns with two different concentrations of saline solution, which gave a concentration factor of about 6. The technology developed can be used for the preparation of clinically applicable 188W/188Re generators using low specfic radioactivity 188W produced in medium flux research reactors. Copyright 2009 © IAEA. All rights reserved
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    Structural characterization by small angle scattering suggests models for monomeric and dimeric forms of full-length ezrin
    (Australian Institute of Nuclear Science and Engineering, 2016-11-29) Phang, JM; Harrop, SJ; Duff, AP; Sokolova, AV; Crossett, B; Walsh, JC; Beckham, SA; Nguyen, CD; Davies, RB; Glöckner, C; Bromley, EH; Wilk, KE; Curmi, PM
    Ezrin is member of the ERM (Ezrin-Radixin-Moesin) family of proteins that have been conserved through metazoan evolution. These proteins have dormant and active forms, there the latter links the actin cytoskeleton to membranes. ERM proteins have three domains: an N-terminal FERM (band Four-point-one ERM) domain comprising three subdomains (F1, F2 and F3); a helical domain; and a C-terminal actin-binding domain. In the dormant form, FERM and C-terminal domains form a stable complex. We have determined crystal structures of the active FERM domain and the dormant FERM:C-terminal domain complex of human ezrin. We observe bistable array of phenylalanine residues in the core of subdomain F3 that is mobile in the active form and locked in the dormant form. As subdomain F3 is pivotal in binding membrane proteins and phospholipids, these transitions may facilitate activation and signaling. Full-length ezrin forms stable monomers and dimers. We used small-angle x-ray scattering to determine the solution structures of these species. As expected, the monomer shows a globular domain with a protruding helical coiled-coil. The dimer shows an elongated dumbbell structure that is twice as long as the monomer. By aligning ERM sequences spanning metazoan evolution, we show that the central helical region is conserved, preserving the heptad repeat. Using this, we have built a dimer model where each monomer forms half of an elongated anti-parallel coiled-coil with domain swapped FERM:C-terminal domain complexes at each end. The model suggests that ERM dimers may bind to actin in a parallel fashion.