| 1. |
- Aneheim, Emma, 1982, et al.
(författare)
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Shelf-Life of e-Lysyl-3-(Trimethylstannyl)Benzamide Immunoconjugates, Precursors for At-211 Labeling of Antibodies
- 2015
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Ingår i: Cancer Biotherapy and Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1084-9785 .- 1557-8852. ; 30:1, s. 41-45
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Tidskriftsartikel (refereegranskat)abstract
- Astatine-211 is possibly the most promising radionuclide for targeted alpha-particle therapy when it comes to the treatment of occult disseminated cancer. Preclinical research has proven effective, and patient studies have been initiated based on these results. However, a lack of production capacity and the complex radiochemistry of At-211 are major obstacles for research and prospective clinical applications. In the present study, astatination of immunoconjugates, already prepared well in advance before radiolabeling, was performed to investigate the possibility of formulating a kit-like reagent for the production of At-211 radiopharmaceuticals. The shelf-life of e-lysyl-3-(trimethylstannyl)benzamide immunoconjugates was evaluated, that is, the effect of different storage times on the quality of the immunoconjugates. The quality being referred to is the capacity to maintain a good radiochemical yield and good cell-binding property after labeling with At-211. The stability of the conjugates was found to be pH dependent with high stability at pH >= 7 and less stability at pH <= 5.5. The immunoconjugates (based on trastuzumab) could be kept for more than 3 months in a phosphate buffered saline solution (pH 7.4) at 4 degrees C before labeling, without compromising the quality of the labeled product. The conjugates are also unaffected by storage at -20 degrees C. Conjugates with a good shelf-life compatible with distant shipping as well as improved radiochemistry are important steps to facilitate further clinical progress with At-211.
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| 2. |
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| 3. |
- Albler, F. J., et al.
(författare)
-
A comparison of two methods of recovering cobalt from a deep eutectic solvent: Implications for battery recycling
- 2017
-
Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 167, s. 806-814
-
Tidskriftsartikel (refereegranskat)abstract
- Progress towards a sustainable industrial process for the recycling of unwanted batteries using a deep eutectic solvent is presented. The effect of lactate anions on the recovery of metals from chloride media by extraction by a lipophilic chloride ionic liquid has been investigated with using solvent extraction experiments with a special emphasis on the behaviour of cobalt and nickel. A new solvent extraction system for the recovery of both cobalt and nickel from acidic (lactic acid) media is presented. The relative impacts of the new extraction system and an aliquat system on both workplace air and the wider environment are compared. The new system was found to pose a smallet threat to both workers and the environment.
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| 4. |
- Ali, Yusuf, et al.
(författare)
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Experimental determination of concentration factors of Ni, Ru and Sb in the model diatom Phaeodactylum tricornutum
- 2023
-
Ingår i: Scientific Reports. - 2045-2322. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes the experimental determination of concentration factors (CF) for nickel, ruthenium and antimony in the model diatom Phaeodactylum tricornutum Bohlin (Bacillariophyceae), which was chosen as a representative of marine phytoplankton. Better determinations of these CF are needed to improve the modelling of marine ecosystems at release points, where radioactive pollutants enter the ecosystem, for more accurate predictions of radiation dose to humans caused by these pollutants. A literature study revealed that the currently implemented values of these CF are based on very scarce data, and a computational sensitivity study showed that the radiation dose caused by radioisotopes of these elements depend strongly on the phytoplankton CF. Nutrient-enriched water samples from Swedish coastal waters were used as a medium for growing of the diatom species P. tricornutum and radioactive isotopes of the studied elements were added to the cultures during the exponential growth phase. The radioactivity in the P. tricornutum and in the culture medium were measured separately and used for determination of CF. Conservative estimates of the CF based on this phytoplankton proxy on the present data are 6400 L/kg for nickel, 20,000 L/kg for ruthenium and 890 L/kg for antimony, with P. tricornutum biomass masses referring to dry weight. The estimates for nickel and ruthenium are similar to previously published values, which underpins the credibility of radiation dose calculations based on these values. The estimate for antimony is uncertain, but also, to our knowledge, represents the first published experimentally based data on this CF.
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| 5. |
- Dubois, Isabelle, 1983, et al.
(författare)
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Dependency of BET surface area on particle size for some granitic minerals.
- 2011
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Ingår i: Proc. Radiochimica Acta. - : Oldenbourg Wissenschaftsverlag. - 2193-2875. ; 1, s. 75-82, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the geochemical retention properties of rocks, which will be the final barrier for radionuclide transport to the biosphere in the case of a failed deep underground repository for spent nuclear fuel, radionuclide sorption experiments are usually made with crushed material. This raises the issue of extrapolating results obtained from laboratory experiments to the field scale. As sorption is generally related to the surface area of the geological material, it is then important to consider the dependency of the specific surface area on the particle size. In this work, BET surface area determinations of samples of different particle sizes are conducted on two minerals commonly found in granite: labradorite and magnetite. The results show a linear relationship between BET surface area and the inverse of the particle size, up to a certain particle size. Furthermore, results also show that the specific surface area for intact, larger pieces is much smaller than the one predicted by a linear extrapolation of results on crushed material. Therefore, extrapolation of BET area for fine particles to the field situation will lead to an overestimation of the surface area and thereby also the radionuclide sorption, if sorption coefficients are extrapolated as well. Also of importance is that these results show that sorption experiments on crushed material may dominantly reflect properties of new surface, created during the mechanically treatment of the samples.
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| 6. |
- Dubois, Isablle E., et al.
(författare)
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Correlation between particle size and surface area for chlorite and K-feldspar
- 2010
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Ingår i: Water-Rock Interaction - Proceedings of the 13th International Conference on Water-Rock Interaction, WRI-13. - 9780415604260 ; , s. 717-720, s. 717-720
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Konferensbidrag (refereegranskat)abstract
- The specific surface area as determined by BET analysis is often used for scaling mineral surface reaction capacities and rates between particles of different sizes as found in nature. Generally, an inverse proportionality between BET area and particle size is assumed, based on geometry. However, macroscopic laboratory studies of mineral surface reactions generally employ crushed material that may have been mechanically disturbed, potentially leading to an artificial increase in the specific surface area, and a change in the apparent surface reactivity. In this study, we determine the BET area for natural K-feldspar and chlorite samples from Sweden as function of particle size in a first step towards relating the surface reactivity for these minerals to grain size.
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| 7. |
- Fachinger, J, et al.
(författare)
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Behaviour of spent HTR fuel elements in aquatic phases of repository host rock formations
- 2006
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Ingår i: Nuclear Engineering and Design. - 0029-5493. ; 236:5-6, s. 543-554
-
Tidskriftsartikel (refereegranskat)abstract
- One back-end option for spent HTR fuel elements proposed for future HTR fuel cycles in the EC is an open fuel cycle with direct disposal ofconditioned or non-conditioned fuel elements. This option has already been chosen in Germany due to the political decision to terminate the useof HTR technology. First integral leaching investigations at Research Centre Juelich on the behaviour of spent HTR fuel in salt brines, typical ofaccident scenarios in a repository in salt, proved that the main part of the radionuclide inventory cannot be mobilised as long as the coated particlesdo not fail. However, such experiments will not lead to a useful model for performance assessment calculations, because a failure of the coatingsby corrosion will not occur during experimental times of a few years. In order to get a robust and realistic model for the long-term behaviour inaqueous phases of host rock systems, it is necessary to understand the barrier function of the different parts of an HTR fuel element, i.e. the matrixgraphite, the different coating materials, and the fuel kernel.Therefore, our attention is focused on understanding and modelling the barrier performance of the different parts of an HTR fuel element withrespect to their barrier function, and on the development of an overall model for performance assessment. In order to understand this behaviour,it is necessary to start with investigations of unirradiated material, and to proceed with experiments with external gamma irradiation to determinethe effects of oxidising radiolysis species. Further experiments with irradiated material have to be performed to investigate the influence of theirradiation damage, and finally an investigation has to be made of the irradiated material plus additional gamma irradiation. Experimental data arenow available for the diffusive transport of radionuclides in the water-saturated graphite pore system, the corrosion rates of unirradiated graphitewith and without external gamma irradiation and unirradiated and irradiated silicon carbide, and for the dissolution rates of UO2 and (Th,U)O2 fuelkernels with and without external gamma irradiation. All investigations were performed in aquatic phases from salt, granite, and clay host rock.
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| 8. |
- Foreman, Mark, 1973, et al.
(författare)
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Activity coefficients in deep eutectic solvents: Implications for the solvent extraction of metals
- 2018
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1369-9261 .- 1144-0546. ; 42:3, s. 2006-2012
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Tidskriftsartikel (refereegranskat)abstract
- An understanding of the effects of the water content on the solvent extraction of metals from the deep eutetic formed from choline chloride and lactic acid has been obtained. This change can be rationalised as being due to a change in the activity coefficient of chloride in the deep eutetic.
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| 9. |
- Hansson, Niklas, 1992, et al.
(författare)
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Influence of groundwater composition on the reductive precipitation of U(VI) on corroding iron foil surfaces
- 2023
-
Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 577
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the disposal of spent nuclear fuel in a deep geological nuclear waste repository, the interactions between U(VI) and corroded iron present in the canister material are of importance. It is important to correctly model the fate of the oxidatively dissolved uranium in order to correctly estimate radium releases from the canister in the long term. The release of radionuclides into the environment depends on the dissolution of the UO2 matrix which is dependent on the redox conditions at the fuel surface. The effect of metallic iron on the reduction of U(VI) was studied under anoxic conditions using synthetic groundwaters with different compositions, chosen to investigate the influence of calcium-uranyl-carbonato complexes on the thermodynamics and kinetics of U(VI) reduction on anoxically corroding iron. The corrosion products formed on the iron surface were investigated using SEM-EDS and XPS to identify elemental composition and oxidation states of uranium and iron on the surface. The iron foils efficiently reduced U(VI) to U(IV) causing its significant sorption and precipitation on the iron foil surfaces in the form of U(IV).
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| 10. |
- Holgersson, Stellan, 1964, et al.
(författare)
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A literature review on thermodynamic sorption models of radionuclides with some selected granitic minerals
- 2023
-
Ingår i: Frontiers in Nuclear Engineering. - 2813-3412. ; 2
-
Forskningsöversikt (refereegranskat)abstract
- The literature for radionuclide sorption on four common granitic minerals have been surveyed. Mainly, such studies were modelling using Thermodynamic Sorption Models were investigated. Although the studies give a far from concerted results, they agree on the necessity to model radionuclide uptake by granitic minerals with a combination of ion exchange and surface complexation reactions. For the sheet-silicates biotite and chlorite alkaline and alkaline earth mainly bind by ion exchange but there is also a clear pH effect for this, which shows the importance of protons competing with metal cations for the exchange sites. For multivalent metal cations, surface complexation is the model of choice since the binding to mineral surfaces seems to be strongly dependent on pH and to be little affected by an increase in ion strength. Anion sorption seems to be taking place also by surface complexation, where the sorption mainly takes place at low pH. For the feldspar minerals K-feldspar and plagioclase the sorption is also modelled by the two reaction mechanisms ion exchange and surface complexation. Surface complexation seems to be especially prevalent for the M(III) and M(VI) state, while ion exchange probably dominates M (II) uptake. Although the literature on these minerals is sparse, the studies show that also these minerals have considerable sorption capacity and must be considered if sorption onto granite is to be modelled from single mineral data. What is usually missing from these studies are more systematic variations in pH, ion strength and temperature. Instead, there is a certain overemphasis on the establishment of sorption isotherms.
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| 11. |
- Holgersson, Stellan, 1964, et al.
(författare)
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Analysis of the metal content of small-size Waste Electric and Electronic Equipment (WEEE) printed circuit-boards part 1: Internet routers, mobile phones and smartphones
- 2018
-
Ingår i: Resources, Conservation and Recycling. - : Elsevier BV. - 0921-3449 .- 1879-0658. ; 133, s. 300-308
-
Tidskriftsartikel (refereegranskat)abstract
- The metal content of printed circuit boards from three types of Waste Electric and Electronic Equipment (WEEE) products were analysed. The products disassembled to retrieve the printed circuit boards (PCBs) were 10 Internet routers, modems and hubs; 30 mobile phones; and 30 smartphones. The collected boards of each product type were milled to 2-3 mm fractions, cryo-milled further and then leached with aqua regia. Leaching solutions were analysed for Ag, Al, As, Au, Be, Bi, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Pd, Pt, Rh, Sb, Sn and Zn. The leaching residues were pyrolysed, fused with LiBO2 and analysed for Al, Ba, Be, Ca, Co, Cr, Fe, K, Mg, Mn, Mo, Na, Nb, P, Sc, Si, Sr, Ti, V, W, Y, Zr and Zn. The results gave a PCB weight of the total product weight of 43% for the routers and 21% for the two phone types. The main constituents of the PCBs were carbon polymers with a concentration of 34%, 30% and 25% for routers, mobile phones and smartphones, respectively and Cu, with a concentration of 22%, 34% and 40% for routers, mobile phones and smartphones, respectively. The concentrations of precious metals, Ag, Au and Pd, in PCBs were found to be 1213 ppm, 199 ppm and 20 ppm for the routers; 2640 ppm, 1051 ppm and 119 ppm for mobile phones; and 2773 ppm, 1083 ppm and 55 ppm for the smartphones, respectively. The concentrations of toxic metals, As, Be, Cr and Pb, in the PCBs were <70 ppm, 0.3 ppm, 506 ppm and 3413 ppm for routers; 93 ppm, 99 ppm, 953 ppm and 3747 ppm for mobile phones; and 141 ppm, 115 ppm, 1306 ppm and 260 ppm for smartphones, respectively. The results demonstrate that for toxic metals, the Pb content is lower in more modern smartphones compared with older mobile phones while the content of other toxic metals are fairly constant. For the routers, the Pb content was similar to the mobile phones, despite the later production year span (2004-2010) compared with the mobile phones (1999-2010). Regarding precious metals the contents of Ag and Au remain at same level when comparing older mobile phones with newer smartphones. Internet routers, modems and hubs are shown to also be a potential source for precious metals, with comparable concentrations to the two phone types if the total product weight is considered.
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| 12. |
- Holgersson, Stellan, 1964, et al.
(författare)
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Biotite dissolution kinetics at pH 4 and 6.5 under anaerobic conditions and the release of dissolved Fe(II)
- 2024
-
Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 662
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Tidskriftsartikel (refereegranskat)abstract
- Dissolution of biotite, the main Fe-bearing mineral in granitic bedrock, is of particular importance for the remediation of reducing conditions after the ingress of oxygen, such as after mining activities or the construction of deep repositories for toxic waste. This study investigated the leaching of biotite of size fraction 0.053–0.075 mm under anaerobic conditions at room temperature and pH 4 and 6.5 for a maximum of 160 days. The changes in the concentrations of the major elements in the leaching solutions were monitored. In addition, Fe(II) was analysed separately. pH-independent rate coefficients kH+ were 4.8∙10−10, 6.9∙10−10, 6.3∙10−11, and 1.0∙10−12 mol1-n m−2 s-1, for Fe, Fe(II), Mn, and Si, respectively. The corresponding proton reaction orders nH+ were 0.61, 0.63, 0.33, and 0.09, respectively. The corresponding parameters for Al were not evaluated because of a suspected gibbsite precipitation at pH 6.5. The dissolution of biotite was found to be incongruent (non-stoichiometric) with respect to both the dissolving elements and the pH value. At pH 4, the dissolution was dominated by the octahedral layer element Fe, whereas at pH 6.5, the dissolution of the tetrahedral element Si dominated. There was no evidence of secondary phase formation, and the biotite leaching rates were consistent with those reported in previous studies conducted under aerobic conditions. In addition, the Fe(III)/Fetot ratio of biotite remained essentially unchanged before and after the experiment. This indicates that the anaerobic conditions alone have little effect on the rate and nature of biotite dissolution, although they may influence vermiculite formation. Therefore, biotite dissolution rates previously obtained under aerobic conditions may also be valid under anaerobic conditions.
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| 13. |
- Holgersson, Stellan, 1964, et al.
(författare)
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Diffusion of HTO and cement pore fluids through host rock
- 2002
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Ingår i: Radiochimica Acta. - 0033-8230. ; 90, s. 99-108
-
Tidskriftsartikel (refereegranskat)abstract
- In the post-closure period of a deep disposal facility for low- to intermediate-level radioactive waste, highly alkaline pore-fluids chemically equilibrated with cementious components of the engineered barriers will migrate into the surroundings. Primary minerals in the host rock could dissolve and secondary calcium silicate hydrate (CSH) phases might be formed in the micro pore system of the rock and change the available porosity for radionuclides and hence the permeability. Since the retardation of radionuclides in the host rock depend on sorption and matrix diffusion, the study of the mineral reactions are of importance. Experiments with diffusion of HTO and synthetic cementitious pore-waters through 1 cm thick discs of Äspö diorite have been made in a nitrogen-flushed glovebox facility. Synthetic cementitious pore-waters representative of fresh and leached concrete were used. For the fresh pore-water the results show that hydroxide ion diffusion is retarded relative to HTO tracer, indicating that reactions between hydroxide and host rock take place. The result can be interpreted as hydroxide sorption in the rock. Al and Si did also accumulate on the sampling side which was attributed to mineral dissolution. For the evolved pore-water no through-diffusion of hydroxide ions or accumulation of other elements in the sampling cell were observed during the sampling period, indicating that the through-diffusion of hydroxide is hindered by this type of pore-water.
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| 14. |
- Holgersson, Stellan, 1964, et al.
(författare)
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Effects of gluco-isosaccharinate on Cs, Ni, Pm and Th sorption onto, and diffusion into cement
- 1998
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Ingår i: Radiochimica Acta. - 0033-8230. ; 82, s. 393-398
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Tidskriftsartikel (refereegranskat)abstract
- The conditions in the Swedish design for a repository of intermediate to low level radioactive waste include a high alkalinity buffer from the concrete construction in combination with cellulose materials in the waste. Experiments have been undertaken in order to quantify the effects of cellulose degradation products on the radionuclide retention capability of the concrete enclosure. Studies of the sorption of Cs, Ni, Pm and Th onto crushed cement and the diffusion of Cs, Ni and Pm in cement and concrete discs of 2 cm thickness were made in a nitrogen-flushed glovebox facility, using different cellulose degradation product additives to the alkaline pore-water. Samples of the liquid phases were taken during a period of 12 months and the sorption and diffusion behaviour was evaluated by radioanalytical methods. In the experiments of alkaline degradation of cellulose the major constituent was found to be D-gluco-isosaccharinate, a potential metal complexing agent, which was synthesized as its Ca salt and used as a 5mM additive in sorption and diffusion experiments. The other additives were leachates of 5 kg/m3 and 100 kg/m3 cellulose in alkaline water. The results show that the additives caused a significant, but transient reduction of the sorption of Pm and Th. The sorption of Cs and Ni were not influenced. The diffusion of D-gluco-isosaccharinate itself was also studied and this indicates that its apparent diffusivity in cement is low, probably due to its strong sorption on cement. This would explain the transient reduction of the radionuclide sorption.
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| 15. |
- Holgersson, Stellan, 1964
(författare)
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Hands-On Model of the Principle of Isotope Dilution Analysis for Use in an Interactive Teaching and Learning Classroom Exercise
- 2021
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Ingår i: Journal of Chemical Education. - : American Chemical Society (ACS). - 0021-9584 .- 1938-1328. ; 98:4, s. 1208-1220
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Tidskriftsartikel (refereegranskat)abstract
- A simple hands-on model for illustrating the concept of isotope dilution analysis (IDA) has been devised. The model consists of two sets of beads of different sizes, with one set representing atoms of the analyte and the other set representing solvent water molecules. Phase separation is mimicked by sieving the beads, and the results are detected according to the color of the analyte beads. In this paper, the following three IDA methods are illustrated using the model: (1) direct IDA, (2) substoichiometric IDA, and (3) IDA-assisted neutron activation analysis. The model was demonstrated for a small group of graduate students with previous knowledge of nuclear chemistry, and the response from an inquiry held after the demonstration was good. It is suggested that the model can be used in a dry chemistry laboratory exercise to demonstrate the methodological differences between the different IDA methods, without the need for costly radioisotopes or irradiation facilities. It can also be used as a tool for engaging students in meta-modeling activities.
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| 16. |
- Holgersson, Stellan, 1964, et al.
(författare)
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Interactions of cement pore fluids with host rock and the effects on HTO, Na and Cs diffusion
- 1998
-
Ingår i: Radiochimica Acta. - 0033-8230. ; 82, s. 197-203
-
Tidskriftsartikel (refereegranskat)abstract
- In the post-closure period of a deep disposal facility for low- and intermediate-level radioactive waste, pore-fluids chemically equilibrated with cementious components of the engineered barriers will migrate into the surroundings. Secondary calcium silicate hydrate (CSH) phases might be formed in the micro pore system of the rocks and change the available porosity for radionuclides and hence permeability. Since the retardation of radionuclides in host rock is dependent on the sorption and matrix diffusion, these chemical reactions are of concern. Experiments have been undertaken to react discs of Äspö diorite with alkaline cement porewaters. These experiments provided aged material for through diffusion experiments and samples for studies of chemical reactions. 1 cm thick discs of Äspö diorite were reacted with waters representative for fresh and leached concrete at 70C in nitrogen filled vessels for six months. Analysis of the waters indicates dissolution of primary minerals and precipitation of secondary CSH phases. HTO, Na and Cs diffusion experiments were then undertaken with both reacted and unreacted discs in a nitrogen-flushed glovebox facility. The effects of alkaline degradation of Äspö diorite on tracer through-diffusion was found to be small and of the same order of magnitude as natural variations in rock heterogenity between undegraded samples.
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| 17. |
- Holgersson, Stellan, 1964
(författare)
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Studies on Batch Sorption Methodologies: Eu Sorption onto Kivetty Granite
- 2012
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Ingår i: Procedia Chemistry. - : Elsevier BV. - 1876-6196. ; 7, s. 629-640
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Konferensbidrag (refereegranskat)abstract
- Six different methodological features of the batch sorption experiment were investigated using 152Eu, Kivetty granite, saline water with initial pH of 8.5, 9 and 10, [Eu]tot=5*10-7M, S:L = 1:20, pre-washing of granite, occasional shaking, centrifugation,wall sorption correction with separate tubes. This gave final Rd= 8.3±2.1, 7.3±2.6 and 8.6±3.7m3/kg at 6 months for each pH,respectively. Then [Eu]tot and S:L were varied, filtration was compared with centrifugation, separate tubes for wall sorption was compared with wall desorption, pre-washing of granite was compared with no washing and two shaking methods werecompared. Two of the investigated methodological features gave too large apparent Rd due to: 1) filter sorption, and 2) low radiotracer concentration, leading to detection problems.
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| 18. |
- Holgersson, Stellan, 1964
(författare)
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Studies on the Effect of Concrete on the Chemistry in a Repository for Radioactive Waste
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden, the disposal method for long-lived low- to intermediate-level radioactive waste is proposed to be the long-term storage of the waste in a concrete repository deep in a geological formation. The use of concrete and steel for the waste containment will affect the chemical conditions inside the repository and in the host rock. In this thesis the expected chemical conditions and their importance on the repository performance are reviewed. The proposed function of the barrier system is described in terms of waste dissolution, diffusion and sorption. The alkaline degradation of cellulose in the waste will produce the complexing agent gluco-isosaccharinic acid (ISA). Experiments made to study the impact of ISA on radionuclide solubility and sorption in cementitious systems are reported. The results show that ISA have a large effect on actinide solubilities but a little effect on their sorption onto concrete, due to the strong sorption of ISA onto concrete. Groundwater will leach alkalihydroxides and portlandite from the concrete barriers. The interactions of the leaching water with the surrounding host rock may influence the properties for radionuclide diffusion in the rock. Primary minerals may dissolve and secondary minerals may precipitate. Experiments with diffusion of alkaline water and radionuclides in rock show that these reactions are very slow in intact rock, but faster at fresh surfaces of the rock. The results also show that the composition of the alkaline water can have a influence on the diffusion of cations in geological media.
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| 19. |
- Horvath, Istvan, 1979, et al.
(författare)
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Interaction between Copper Chaperone Atox1 and Parkinson's Disease Protein α-Synuclein Includes Metal-Binding Sites and Occurs in Living Cells
- 2019
-
Ingår i: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 10:11, s. 4659-4668
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Tidskriftsartikel (refereegranskat)abstract
- Alterations in copper ion homeostasis appear coupled to neurodegenerative disorders, but mechanisms are unknown. The cytoplasmic copper chaperone Atox1 was recently found to inhibit amyloid formation in vitro of α-synuclein, the amyloidogenic protein in Parkinson's disease. As α-synuclein may have copper-dependent functions, and free copper ions promote α-synuclein amyloid formation, it is important to characterize the Atox1 interaction with α-synuclein on a molecular level. Here we applied solution-state nuclear magnetic resonance spectroscopy, with isotopically labeled α-synuclein and Atox1, to define interaction regions in both proteins. The α-synuclein interaction interface includes the whole N-terminal part up to Gln24; in Atox1, residues around the copper-binding cysteines (positions 11-16) are mostly perturbed, but additional effects are also found for residues elsewhere in both proteins. Because α-synuclein is N-terminally acetylated in vivo, we established that Atox1 also inhibits amyloid formation of this variant in vitro, and proximity ligation in human cell lines demonstrated α-synuclein-Atox1 interactions in situ. Thus, this interaction may provide the direct link between copper homeostasis and amyloid formation in vivo.
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| 20. |
- Insulander Björk, Klara, 1982, et al.
(författare)
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Effect of the thorium oxide content on the leaching of a mixed thorium-uranium oxide fuel
- 2022
-
Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 331, s. 2849-2857
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Tidskriftsartikel (refereegranskat)abstract
- Leaching of uranium from uranium oxide fuel in contact with water can be a radiation hazard problem in the case of fuel cladding failure, either during nuclear reactor operation or in an interim storage, as well as in a final repository. One way to mitigate this is to reduce the solubility of the fuel matrix by the mixing uranium oxide with a compound which is less soluble but otherwise of similar properties. In this paper, the effect of thorium oxide content on the leaching of the uranium oxide matrix is investigated. The method was to study the leaching of the uranium oxide fuel matrix as a function of a varying content of thorium oxide, using materials manufactured by powder co-milling. It was found that the substitution of more than 25% UO2 with ThO2 reduces the matrix leaching by more than one order of magnitude in most of the different leaching solutions investigated. The substitution of 7% UO2 with ThO2 results in a reduction of matrix leaching by 10–90%, depending on the concentration of borate and dissolved oxygen in the leaching solution.
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| 21. |
- Insulander Björk, Klara, 1982, et al.
(författare)
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Experimental determination of concentration factors of Mn, Zn and I in the phytoplankton species Phaeodactylum Tricornutum
- 2023
-
Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 261
-
Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic radionuclides released into the environment cause a radiation dose to wildlife and humans which must be quantified, both to assess the effect of normal releases, and to predict the consequences of a larger, unplanned release. To estimate the spread of the radioactive elements, the ecosystem around release points is modelled, and element uptake is usually quantified by concentration factors (CF), which relates the concentration of an element in an organism to the concentration of the same element in a medium under equilibrium conditions. In this work, we experimentally determine some phytoplankton CF that are needed for improved modelling of the marine ecosystems around nuclear facilities and release points. CFs that require better determination have been identified through literature search. Sensitivity studies, using the currently used ecosystem modelling software PREDO, show that for most studied groups, the dose committed by the respective radionuclides is almost proportional to the corresponding phytoplankton CFs. In the present work, CFs are determined through laboratory experiments with cultured phytoplankton and radionuclides of the concerned elements, assessing the element uptake by the phytoplankton through detection of the emitted radiation. The three CF assessed in this work were those for manganese, zinc and iodine in phytoplankton. Conservative estimates of these CF based on the present data are 40 000 L/kg for manganese, 50 000 L/kg for zinc and 180 L/kg for iodine with the phytoplankton masses referring to their dry weight.
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| 22. |
- Li, Xiaodong, et al.
(författare)
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Sorption of Se species on mineral surfaces, part I: Batch sorption and multi-site modelling
- 2018
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Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 95, s. 147-157
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Tidskriftsartikel (refereegranskat)abstract
- The sorption behavior of Se(IV) on Grimsel granodiorite and its main minerals, plagioclase, K-feldspar, quartz and biotite, were investigated in Grimsel groundwater simulant in a large Se concentration range (from 1.66 × 10−10M to 1 × 10−3M). Experimental results show that the distribution coefficients (Kdvalues) of Se(IV) on the rock and mineral samples increased with the decreasing of Se(IV) concentration. The sorption of Se(IV) on biotite has the largest Kdvalue in low concentration area (<10−7M) stabilizing between 0.0595 ± 0.0097 m3/Kg and 0.0713 ± 0.0164 m3/Kg. The Kdvalue of Se(IV) on K-feldspar was the second largest (0.0154 ± 0.0019 m3/Kg in 10−9M) while the sorption on quartz was negligible. The sorption behavior of Se(IV) on Grimsel granodiorite followed the same trend as plagioclase, the most abundant mineral in Grimsel granodiorite, with Kdvalues of 0.0078 ± 0.0010 m3/Kg for Grimsel granodiorite and 0.0085 ± 0.0016 m3/Kg for plagioclase, when Se(IV) concentration was 10−9M. HPLC-ICP-MS results show that all the Se(IV) remained in +IV oxidation state after more than 1 month experimental time and speciation modelling proved that the main species in Grimsel groundwater simulant were HSeO3−and SeO32−. Multi-site surface complexation modelling was performed by PHREEQC with the help of molecular modelling techniques which was performed with the CASTEP code implemented into Materials Studio. The modelling results predict that there are three kinds of sorption sites on the surface of biotite mineral, with sorption site densities differing in three magnitudes.
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| 23. |
- Muuri, E., et al.
(författare)
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Behavior of Cs in Grimsel granodiorite: sorption on main minerals and crushed rock
- 2016
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Ingår i: Radiochimica Acta. - : Walter de Gruyter GmbH. - 0033-8230 .- 2193-3405. ; 104:8, s. 575-582
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Tidskriftsartikel (refereegranskat)abstract
- In this study the sorption of cesium was investigated on four different minerals; quartz, plagioclase, potassium feldspar and biotite as well as granodiorite obtained from the Grimsel test site in Switzerland. The experiments were conducted in the presence of the weakly saline Grimsel groundwater simulant by determining the distribution coefficients using batch sorption experiments and PHREEQC-modelling across a large concentration range. In addition, the purity of the minerals was measured by XRD and the specific surface areas by BET method using krypton. The distribution coefficients of cesium were largest on biotite (0.304 +/- 0.005 m(3)/kg in 10(-8) M). Furthermore, the sorption of cesium on quartz was found to be negligibly small in all investigated concentrations and the sorption of cesium on potassium feldspar and plagioclase showed similar behavior against a concentration isotherm with distribution coefficients of 0.0368 +/- 0.0004 m(3)/kg and 0.18 +/- 0.04 m(3)/kg in 10(-8) M. Finally, cesium sorption behavior on crushed granodiorite followed the trend of one of its most abundant mineral, plagioclase with distribution coefficient values of 0.107 +/- 0.003m(3)/kg in 10-8 M. At low concentrations (< 1.0 . 10(-6) M) cesium was sorbed on the frayed edge sites of biotite and once these sites are fully occupied cesium sorbs additionally to the Type II and Planar sites. As a consequence, the sorption of cesium on biotite is decreased at concentrations > 1.0 . 10(-6) M. Secondly cesium sorption on potassium feldspar and plagioclase showed similar non-linear behavior with varying concentration. The results were used to assist the interpretation of cesium diffusion process in the 2.5 year in-situ experiment carried out in the underground laboratory at Grimsel test site in Switzerland (2007-2009).
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| 24. |
- Söderlund, Mervi, et al.
(författare)
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Sorption and speciation of selenium in boreal forest soil
- 2016
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Ingår i: Journal of Environmental Radioactivity. - : Elsevier BV. - 0265-931X .- 1879-1700. ; 164, s. 220-231
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Tidskriftsartikel (refereegranskat)abstract
- Sorption and speciation of selenium in the initial chemical forms of selenite and selenate were investigated in batch experiments on humus and mineral soil samples taken from a 4–m deep boreal forest soil excavator pit on Olkiluoto Island, on the Baltic Sea coast in southwestern Finland. The HPLC–ICP-MS technique was used to monitor any possible transformations in the selenium liquid phase speciation and to determine the concentrations of selenite and selenate in the samples for calculation of the mass distribution coefficient, Kd, for both species. Both SeO3 2− and SeO4 2− proved to be resistant forms in the prevailing soil conditions and no changes in selenium liquid phase speciation were seen in the sorption experiments in spite of variations in the initial selenium species, incubation time or conditions, pH, temperature or microbial activity. Selenite sorption on the mineral soil increased with time in aerobic conditions whilst the opposite trend was seen for the anaerobic soil samples. Selenite retention correlated with the contents of organic matter and weakly crystalline oxides of aluminum and iron, solution pH and the specific surface area. Selenate exhibited poorer sorption on soil than selenite and on average the Kd values were 27–times lower. Mineral soil was more efficient in retaining selenite and selenate than humus, implicating the possible importance of weakly crystalline aluminum and iron oxides for the retention of oxyanions in Olkiluoto soil. Sterilization of the soil samples decreased the retention of selenite, thus implying some involvement of soil microbes in the sorption processes or a change in sample composition, but it produced no effect for selenate. There was no sorption of selenite by quartz, potassium feldspar, hornblende or muscovite. Biotite showed the best retentive properties for selenite in the model soil solution at about pH 8, followed by hematite, plagioclase and chlorite. The Kd values for these minerals were 18, 14, 8 and 7 L/kg, respectively. It is proposed that selenite sorption is affected by the structural Fe(II) in biotite, which is capable of inducing the reduction of SeO3 2− to Se(0). Selenite probably forms a surface complex with Fe(III) atoms on the surface of hematite, thus explaining its retention on this mineral. None of the minerals retained selenate to any extent.
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| 25. |
- Teknetzi, Ioanna, 1992, et al.
(författare)
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An environmentally friendly method for selective recovery of silver and ITO particles from flexible CIGS solar cells
- 2024
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Ingår i: Sustainable Materials and Technologies. - 2214-9937. ; 39
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Tidskriftsartikel (refereegranskat)abstract
- While the share of solar energy harvesting by photovoltaic (PV) systems in electricity production increases, their recycling still remains mainly at an early stage. Therefore, valuable and critical elements like silver (Ag) and indium (In) are lost along with production and end-of-life waste, highlighting the need for simple and sustainable recycling solutions which could be easily implemented by the industry. In this paper, we suggest a simple environmentally friendly method for selective recovery of Ag and Indium Tin Oxide (ITO) particles from flexible Copper Indium Gallium diSelenide (CIGS) solar cells, using two-step ultrasonic (US) leaching with low nitric acid (HNO3) concentration of 0.1 M. The first step aimed at the selective liberation of ITO through the selective dissolution of the zinc-rich layer underneath, using low US power for 3 min. In the second step, the same conditions as in the first step were applied, but now using high US power for 15 min for removal of the Ag grid lines. Both the ITO and the Ag grid particles were subsequently recovered by filtration and there was no loss of Ag observed in the leachates. By this method, a complete separation of ITO and Ag from the solar cell was achieved, with no changes in their crystal structure and promising purities of about 70.5 wt% and 95.0 wt%, respectively. This new approach opens up a new path for possible direct reuse of these materials in the manufacturing of new PVs, after further purification, with an impressively low need for chemicals.
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| 26. |
- Teknetzi, Ioanna, 1992, et al.
(författare)
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Valuable metal recycling from thin film CIGS solar cells by leaching under mild conditions
- 2023
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248. ; 252
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Tidskriftsartikel (refereegranskat)abstract
- The increase in the manufacturing of copper-indium-gallium-diselenide (CIGS) thin film photovoltaics is accompanied by a growing amount of production waste, which contains a mixture of valuable, critical and hazardous elements. However, industrial recovery and reuse processes of these elements for production of new photovoltaics are still absent. In this paper, the possibility of using benign leaching conditions for recovering mainly silver and indium from production waste flexible CIGS solar cells was investigated, along with the contamination levels from other industrial elements in the leachate. At the same time, the prospect of selective leaching of contaminants was assessed, aiming to purer streams of the valuable metals and thus their reuse in new products. The results show an increase in the leaching yields of Ag and In when acid concentration and surface to liquid ratio (A:L) increase, however, this is also true for contamination. A complete Ag recovery and 85% recovery of In was achieved with 2 M HNO3 and A:L equal to 1:3 cm2/ml after 24 h of leaching at room temperature. Under the same conditions, leaching with 0.5 M HNO3 extracts 85% Ag and 30% In, with correspondingly reduced contamination levels. Finally, leaching with 0.1 M HNO3 proved to be promising for achievement of higher Ag purity through an initial step of Zn selective leaching for 1 h.
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| 27. |
- Zhang, Xiaolu, 1983, et al.
(författare)
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Memo1 binds reduced copper ions, interacts with copper chaperone Atox1, and protects against copper-mediated redox activity invitro
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 119:37
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Tidskriftsartikel (refereegranskat)abstract
- The protein mediator of ERBB2-driven cell motility 1 (Memo1) is connected to many signaling pathways that play key roles in cancer. Memo1 was recently postulated to bind copper (Cu) ions and thereby promote the generation of reactive oxygen species (ROS) in cancer cells. Since the concentration of Cu as well as ROS are increased in cancer cells, both can be toxic if not well regulated. Here, we investigated the Cu-binding capacity of Memo1 using an array of biophysical methods at reducing as well as oxidizing conditions invitro. We find that Memo1 coordinates two reduced Cu (Cu(I)) ions per protein, and, by doing so, the metal ions are shielded from ROS generation. In support of biological relevance, we show that the cytoplasmic Cu chaperone Atox1, which delivers Cu(I) in the secretory pathway, can interact with and exchange Cu(I) with Memo1 invitro and that the two proteins exhibit spatial proximity in breast cancer cells. Thus, Memo1 appears to act as a Cu(I) chelator (perhaps shuttling the metal ion to Atox1 and the secretory path) that protects cells from Cu-mediated toxicity, such as uncontrolled formation of ROS. This Memo1 functionality may be a safety mechanism to cope with the increased demand of Cu ions in cancer cells.
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