| 1. |
- Modin, A., et al.
(författare)
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Closed source experimental system for soft x-ray spectroscopy of radioactive materials
- 2008
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 79:9, s. 093103-
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Tidskriftsartikel (refereegranskat)abstract
- An instrumental and experimental setup for soft x-ray spectroscopy meeting the requirements of a closed source for radioactivity is described. The system consists of a vacuum sealed cell containing the sample, mounted on a tubing system to ensure compatibility with most standard manipulators. The soft x rays penetrate a thin x-ray window separating the interior of the cell from the vacuum in the experimental chamber. Our first results for single crystal PuO2 confirm the feasibility of experiments using the setup. The results are consistent with results of first principles calculations and previously recorded spectra obtained using a standard open source setup. The results show that the closed source experimental system can be used to collect valuable experimental data from radioactive materials.
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| 2. |
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| 3. |
- Lindegren, Sture, 1960, et al.
(författare)
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Synthesis and biodistribution of 211At-labeled, biotinylated, and charge-modified poly-L-lysine: evaluation for use as an effector molecule in pretargeted intraperitoneal tumor therapy.
- 2002
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Ingår i: Bioconjugate chemistry. - 1043-1802 .- 1520-4812. ; 13:3, s. 502-9
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Tidskriftsartikel (refereegranskat)abstract
- Poly-L-lysine (7, 21, and 204 kDa) has been evaluated as an effector carrier for use in pretargeted intraperitoneal tumor therapy. For the synthesis, the epsilon-amino groups on the poly-L-lysine were modified in three steps utilizing conjugate biotinylation with biotin amidocaproate N-hydroxysuccinimide ester (BANHS), conjugate radiolabeling with (211)At using the intermediate reagent N-succinimidyl 3-(trimethylstannyl)benzoate (m-MeATE), and charge modification using succinic anhydride, resulting in an increase in the molecular weight of approximately 80% of the final product. The labeling of the m-MeATE reagent and subsequent conjugation of the polymer were highly efficient with overall radiochemical yields in the range of 60-70%. The in vitro avidin binding ability of the modified polymer was almost complete (90-95%), as determined by binding to avidin beads using a convenient filter tube assay. Following intraperitoneal (ip) injection in athymic mice, the 13 kDa polymer product was cleared mainly via the kidneys with fast kinetics (biological half-live T(b) approximately 2 h) and with low whole-body retention. The clearance of the 38 kDa polymer was distributed between kidneys and liver, and the 363 kDa polymer was mainly sequestered by the liver with a T(b) of 8 h. Increased tissue uptake in the thyroid, lungs, stomach, and spleen following the distribution of the large effector molecules (38 and 363 kDa) suggests that degradation of the polymers by the liver may release some of the label as free astatine/astatide.
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| 4. |
- Retegan Vollmer, Teodora, 1979, et al.
(författare)
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Extraction of actinides with different 6,60-bis(5,6-dialkyl-[1,2,4]-triazin-3-yl)[2,20]-bipyridines (BTBPs)
- 2007
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Ingår i: SOLVENT EXTRACTION AND ION EXCHANGE. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 25:4, s. 417-431
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Tidskriftsartikel (refereegranskat)abstract
- The extraction of Am(III), Th(IV), Np(V), and U(VI) from nitric acid by 6,6′‐bis(5,6‐dialkyl‐[1,2,4]‐triazin‐3‐yl)‐[2,2′]‐bipyridines (C2‐, C4‐, C5‐, and CyMe4‐BTBP) was studied. Since only americium and neptunium extraction was dependent on the BTBP concentration, computational chemistry was used to explain this behavior. It has been shown that the coordination of the metal played an important role in forming an extractable complex into the organic phase, thus making it possible to extract pentavalent and trivalent elements from tetravalent and hexavalent elements. This is very important, especially because it shows other possible utilizations of a group of molecules meant to separate the actinides from the lanthanides. In addition, the level of extraction at very low or no BTBP concentration was explained by coordination chemistry.
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| 5. |
- Wennerberg, Ann, 1955, et al.
(författare)
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In vivo stability of hydroxyapatite nanoparticles coated on titanium implant surfaces.
- 2011
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Ingår i: The International journal of oral & maxillofacial implants. - 1942-4434. ; 26:6, s. 1161-6
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Nanotechnology has been employed in attempts to enhance bone incorporation of dental implants. Often, nanoparticles are applied to the implant surface as particle coatings. However, the same properties that may increase the functionality may also lead to undiscovered negative effects, such as instability of the nanocoating. The aim of this study was to investigate the stability÷instability of the nanoparticles using a radiolabeling technique. Materials and Methods: Twenty threaded and turned titanium microimplants were inserted in 10 rats. All 20 implants were coated with nanometer-sized hydroxyapatite (HA) particles. In order to trace the HA nanoparticles, the particles for 16 implants were labeled with calcium 45 (45Ca). After 1, 2, 4, and 8 weeks, the implants and surrounding bone were retrieved and analyzed using autoradiography with respect to particle migration from the implant surface. Samples from the brain, liver, thymus, kidney, and blood, as well as wooden shavings from the rats' cages, were also retrieved and analyzed using liquid scintillation counting. Results: The radioactivity representing the localization of 45Ca decreased over time from the vicinity of the implant. The amounts of 45Ca found in the blood and in the rats' excretions decreased with time and corresponded well to each other. After 8 weeks, the only trace of 45Ca was found in the liver. Conclusion: The results indicated that released particles leave the body through the natural cleaning system, and the probability that the nanocoating will assemble in vital organs and thus become a potential biologic risk factor is unlikely. Int J Oral Maxillofac Implants 2011;26:1161-1166.
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| 6. |
- Ekberg, Christian, 1967, et al.
(författare)
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The structure of plutonium(IV) oxide as hydrolysed clusters in aqueous suspensions
- 2013
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 42:6, s. 2035-2040
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of plutonium still puzzles scientists 70 years after its discovery. There are several factors making the chemistry of plutonium interesting including its ability to keep several oxidation states. Another unique property is that the oxidation states +III, +IV, +V and +VI may exist simultaneously in solution. Another property plutonium shares with some other tetravalent metal ions is the ability to form stable polynuclear complexes or colloids. The structures of freshly prepared and five-year old plutonium(IV) colloids are compared with crystalline plutonium(IV) oxide using Pu L-3-edge EXAFS. It was shown that as the plutonium colloids age they do in fact shrink in size, contrary to previous expectations. The aged colloidal particles are indeed very small with only 3-4 plutonium atoms, and with a structure very similar to solid plutonium(IV) oxide, but with somewhat shorter mean Pu-O bond and Pu. Pu distances indicating a partial oxidation. The very small size of the colloidal particles is further supported by the fact that they do not sediment on heavy ultra-centrifugation.
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| 7. |
- Hedström, Hanna, 1983, et al.
(författare)
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Characterization of Radium Sulphate
- 2013
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Ingår i: Journal of Nuclear Chemistry. - : Hindawi Limited. - 2314-4831 .- 2314-4955. ; 2013, s. Art. no. 940701-
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the crystal structure of radium sulphate and compares its structure to barium sulphate, strontium sulphate, and lead sulphate. The radium sulphate powder was measured by both powder X-ray diffraction and EXAFS. The unit cell was determined to be orthorhombic, belonging to the Pnma (no. 62) space group with the cell parameters ? = 9.07A, ˚ ? = 5.52A, ˚ ? = 7.28A, and ˚ ? = 364.48A˚ 3 . These data support the fact that radium sulphate is isostructural with barium, strontium, and lead sulphate. The bond distances were determined using EXAFS. The mean Ra–O and S–O bond distances were found to be 2.96(2)A˚ and 1.485(8)A, respectively, and the Ra–O–S bond angle was ˚ 127(2)∘ . Findings of EXAFS data are quite consistent and support the XRD data. These findings show that it is possible for radium to coprecipitate with barium, strontium, and lead in sulphate media to form a substitutional solid solution.
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| 8. |
- Johnsson, Anna, 1975, et al.
(författare)
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Leaching of spent nuclear fuel in the presence of siderophores
- 2009
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 279:2, s. 619-626
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Tidskriftsartikel (refereegranskat)abstract
- Metal species that are dissolved in water can be transported in the environment, because they can be mobile. Microorganisms can affect metal mobility by excreting organic ligands with high metal affinity. Siderophores are organic ligands with high affinities for Fe 3+ . They are also able to form complexes with other metals such as actinides. Many countries plan to deposit spent nuclear fuel in deep geological repositories. Microorganisms are present in these subterranean environments and could potentially affect the repository. In this study, the effect of microbial siderophores on the dissolution behavior of two fragments of a spent nuclear fuel pellet was investigated. The commercial hydroxamate siderophore, deferoxamine mesylate (DFAM), and pyoverdin siderophores, isolated from cultures of Pseudomonas fluorescens (CCUG 32456A), were used. DFAM and lyophilized pyoverdins were dissolved in synthetic groundwater to final concentrations of 10 μM and 2.5·10 -2 g·L -1 , respectively. The fuel pellet fragments were kept in sealed pressure vessels at 10 bars of H 2 . The pyoverdin solution was first tested, followed by the DFAM solution and the pure synthetic groundwater. Samples were taken on 0, 1, 5, 9 and 14 days after changing the solution in the pressure vessels. The elemental composition of samples was analyzed by means of ICP-MS. The pyoverdin solution maintained significantly higher concentrations of Np and Pu than the pure synthetic groundwater. On the 14 th day the concentrations of Np and Pu in the pure synthetic groundwater were 0.01 nM and 0.13 nM, respectively, compared to 0.02 nM and 0.31 nM in the pyoverdin solution. Furthermore, spent nuclear fuel samples were observed to release Ru in the presence of both pyoverdin and DFAM. Hence, it seems that siderophores can form complexes with elements present in spent nuclear fuel. © 2008 Akadémiai Kiadó.
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