Browsing by Author "Zaw, M"

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    Alternative chromatographic processes for no-carrier added 177Lu radioisotope separation Part I. Multi-column chromatographic process for clinically applicable
    (Springer, 2008-09-01) Le, VS; Morcos, N; Zaw, M; Pellegrini, PA; Greguric, ID
    The conventional multi-column solid phase extraction (SPE) chromatography technique using di-(2-ethylhexyl)orthophosphoric acid (HDEHP) impregnated OASIS-HLB sorbent based SPE resins (OASIS-HDEHP) was developed for the separation of no-carrier added (n.c.a) Lu-177 from the bulk quantity of ytterbium target. This technique exploited the large variation of lutetium metal ion distribution coefficients in the varying acidity of the HCl solution-OASIS-HDEHP resin systems for the consecutive loading-eluting cycles performed on different columns. The production batches of several hundred mCi n.c.a Lu-177 radioisotope separated from 50 mg Yb target activated in a nuclear reactor of medium neutron nux (Phi = 5 center dot 10(13) n.cm(-2).s(-1)) were successfully performed using the above mentioned separation technique. With the target irradiation in a reactor of thermal neutron flux Phi = 2 center dot 10(14) n.cm(-2).s(-1) or the parallel run of several separation units, many Ci-s of n.c.a Lu-177 can be profitably produced. The OASIS-HDEHP resin based multi-column SPE chromatography technique makes the separation process simple and economic and offers an automation capability for operation in highly radioactive hazardous environments. © 2008, Springer.
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    Alternative chromatographic processes for no-carrier added 177Lu radioisotope separation Part II. The conventional column chromatographic separation combined with HPLC for high purity
    (Springer, 2008-09-01) Van So, L; Morcos, N; Zaw, M; Pellegrini, PA; Greguric, ID; Nevissi, A
    HPLC technique combined with the simple conventional column solid phase extraction (SPE) chromatography using di-(2-dethylhexyl)orthophosphoric acid (HDEHP) impregnated OASIS-HLB sorbent based SPE resins (OASIS-HDEHP ) was developed for the separation of no-carrier added (n.c.a) 177Lu from the bulk quantity of ytterbium target. This combination strategy was based on combining the advantages of the better resolution of HPLC separation of n.c.a 177Lu from the few milligram level Yb target with the high capacity of the OASISHDEHP column for the separation of 177Lu from the bulk Yb target. The production batches of several hundred mCi activity of n.c.a 177Lu radioisotope separated from 50 mg Yb target activated in a nuclear reactor of medium neutron flux (Φ = 5.1013 n.cm–2.s–1) were successfully performed using this combined separation technique. With the target irradiation in a reactor of higher thermal neutron flux or with the parallel run of several separation units, several Ci-s of n.c.a 177Lu can be profitably produced on a commercial production basis. © 2008, Springer.
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    Alternative method for Cu-64 radioisotope production
    (Elsevier, 2008-05-12) Le, VS; Howse, J; Zaw, M; Pellegrini, PA; Katsifis, A; Greguric, ID; Weiner, R
    The method for 64Cu production based on a 64Ni target using an 18 MeV proton energy beam was developed. The studies on the optimisation of targetry for the 18 MeV proton bombardments were performed in terms of the cost-effective target utilisation and purity of the 64Cu product. The thickness-specific 64Cu yield (μCi/(μA×μm)) was introduced into the optimisation calculation with respect to cost-effective target utilisation. A maximum target utilisation efficacy factor (TUE) was found for the proton energy range of 2.5–13 MeV with corresponding target thickness of 36.2 μm. With the optimised target thickness and proton energy range, the 64Ni target thickness saving of 45.6% was achieved, while the overall 64Cu yield loss is only 23.9%, compared to the use of the whole effective proton energy range of 0–18 MeV with target thickness of 66.6 μm. This optimisation has the advantage of reducing the target amount to a reasonable level, and therefore the cost of the expensive 64Ni target material. The 64Ni target electroplated on the Au–Tl multi layer coated Cu-substrate was a new and competent design for an economic production of high quality 64Cu radioisotope using an 18 MeV proton energy cyclotron or a 30 MeV cyclotron with proton beam adjustable to 18 MeV. In this design, the Au coating layer plays a role of protection of “cold” Cu leakage from the Cu substrate and Tl serves to depress the proton beam energy (from 18 MeV to the energy optimised value 13 MeV). The ion exchange chromatographic technique with a gradient elution was applied to improve the 64Cu separation with respect to reducing the processing time and control of 64Cu product quality. © 2009, Elsevier Ltd.
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    Development of 68Ga generator at ANSTO
    (Medknow Publications, 2011-06-23) Le, VS; Izard, M; Pellegrini, PA; Zaw, M
    A 68 Ge/ 68 Ga generator combined with automated 68 Ga eluate purification unit was developed to produce 68 Ga solution suitable for labelling peptide ligands for PET radiopharmaceutical applications. The sorbent of a Ti-Zr ceramic structure [1] was used as a generator column packing material. 68 Ga eluate of around 5 mL volume in 0.1 M HCl solution was purified on a small cation exchanger column with an aqueous alcohol solution mixture of hydrochloric acid, ascorbic acids and halide salts. An alkali solution was used for elution of 68 Ga from the ion exchange resin column to obtain a purified 68 Ga solution which is conditioned with acidic solutions to obtain a final 68 Ga product of pH=3-4 in 0.75 mL 0.5 M NaCl or 0.5 M sodium acetate solution. The organic solvent free 68 Ga solution product of acidity suitable for coordination chemistry based labelling of the peptide ligands was successfully used for preparation of DOTATATE and DOTATOC PET radiopharmaceuticals. The process of 68 Ga elution from the generator followed by 68 Ga eluate purification was performed using a low-cost automation bench-top system. [2] This system is designed based on the timing sequence of seven processing steps without feedback control. The variable flow rate of eluents used for elution/purification in this system also ensure the optimisation of operating times with respect to different adsorption/ desorption kinetics of 68 Ga ion species, which is controlled by the sorbent and ion exchange resin used in the generator and purification columns. © 2011, Medknow publication
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    Seasonal changes of redox potential and microbial activity in two agricultural soils of tropical Australia: some implications for soil-to-plant transfer of radionuclides
    (Elsevier, 2004-05-14) Twining, JR; Zaw, M; Russell, RA; Wilde, KL
    Very little is known of the factors controlling soil-to-plant transfer of radionuclides in tropical environments. As part of an IAEA/FAO coordinated research project (CRP) designed to elucidate some of those factors, near-surface samples of two agricultural red-earth soils (Blain and Tippera) were collected from a study site in the Northern Territory. The climate is tropical monsoonal with crops being grown over the wet season from December to March/April. It is important to understand soil variables that may be related to this dramatic seasonality. In this investigation, soil redox state and microbial populations were assessed before and after the growing season with a view to generating hypotheses for future evaluation. The X-ray absorption near edge structure (XANES) technique was used to determine overall changes in the solid-state redox speciation of Fe and Mn in soils across the growing period. Fe speciation did not change but approximately 10% of the total Mn was oxidised from Mn(II) to Mn(III) and Mn(IV) in both soils between October 1999 and April 2000. An apparent disconnect between Fe and Mn was not unexpected given the >10 times higher concentration of Fe in the soils compared with Mn. These results have implications for the bioavailability of redox sensitive radionuclides such as Tc and Pu. Similarly, microbial population estimates were derived before and after the growing period. Total bacterial populations did not vary from 106 to 107 colonies per gram. Fungal populations increased over the growing season from 3–6×105 to 1–4×106 colonies per gram of soil. Fungi have the potential to decrease soil pH and hence increase the bioavailability of radionuclides such as Cs. In addition, fungi act to facilitate plant nutrition. This could lead to enhanced accumulation of nutrient analogues (e.g. Sr and Ra for Ca; Tc for Mn), but this effect may be masked by improved biomass production. © 2004 Elsevier Ltd