| 1. |
- Amme, Marcus, et al.
(författare)
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Combined effects of Fe(II) and oxidizing radiolysis products on UO2 and PuO2 dissolution in a system containing solid UO2 and PuO2
- 2012
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 430:1-3, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- The stability of UO2 spent nuclear fuel in an oxygen-free geological repository depends on the absence of oxidizing reaction partners in the near field. This work investigates the reactions between the products of water radiolysis by alpha radiation and Fe(II) an the effect on UO2 dissolution. Solid (PuO2)-Pu-238 powder and UO2 pellet were allowed to react in Fe(II) solution in oxygen-free batch reactor tests and kinetics of the subsequent redox reactions were measured. Depending on the concentration of Fe(II) (tests with 10(-5) and 10(-4) mol L-1 were made), the induced redox reactions took place between 20 and 400 h. Dissolved uranium concentrations went first through a minimum caused by reduction, followed by a maximum caused by radiolytic oxidation, and eventually reached another minimum, probably due to sorption on precipitated Fe(III). Plutonium concentrations were decreasing steadily after going through a maximum about 70 h from the start of the experiments. The results show that in the presence of the strong alpha-radiolytic field induced by the presence of solid Pu-238, the behavior of the system is largely governed by Fe(II) as it controls the H2O2 concentration, reduces U(VI) in solution and drives the Fenton reaction leading to the oxidation of Pu(IV).
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| 2. |
- Ekeroth, Ella, et al.
(författare)
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The relative impact of radiolysis products in radiation induced oxidative dissolution of UO2
- 2006
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 355:1-3, s. 38-46
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Tidskriftsartikel (refereegranskat)abstract
- The relative impact of radiolysis products in radiation induced oxidative dissolution Of UO2 has been studied experimentally. The experiments were performed by y-irradiating an aqueous solution containing HCO3 and a UO2-pellet. The U(VI) concentration in the solution was measured as a function of irradiation time. The aqueous solution was saturated with Ar, N2O, N2O/O-2 (80/20), air and O-2 in order to vary the conditions and the initial oxidant yields. The measured rate of oxidation was significantly higher for the O-2- and air saturated systems compared to the other systems. Using oxidant concentrations derived from numerical simulations of the corresponding homogeneous systems and previously determined rate constants for oxidation Of UO2, the relative trend in rate of oxidation in the different systems was reproduced. The results from the simulations were also used to estimate the relative impact of the oxidative radiolysis products as a function of irradiation time, both for gamma- and alpha-irradiated systems. For 7-irradiated systems saturated with Ar, air or 02, the most important oxidant is H2O2 while for N2O- and N2O/O-2-saturated systems the most important oxidant is CO3.-. For a-irradiated systems the most important oxidant was found to be H2O2.
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| 3. |
- Hart, Traver, et al.
(författare)
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High-Resolution CRISPR Screens Reveal Fitness Genes and Genotype-Specific Cancer Liabilities
- 2015
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Ingår i: Cell. - : Elsevier BV. - 0092-8674 .- 1097-4172. ; 163:6
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Tidskriftsartikel (refereegranskat)abstract
- The ability to perturb genes in human cells is crucial for elucidating gene function and holds great potential for finding therapeutic targets for diseases such as cancer. To extend the catalog of human core and context-dependent fitness genes, we have developed a high-complexity second-generation genome-scale CRISPR-Cas9 gRNA library and applied it to fitness screens in five human cell lines. Using an improved Bayesian analytical approach, we consistently discover 5-fold more fitness genes than were previously observed. We present a list of 1,580 human core fitness genes and describe their general properties. Moreover, we demonstrate that context-dependent fitness genes accurately recapitulate pathway-specific genetic vulnerabilities induced by known oncogenes and reveal cell-type-specific dependencies for specific receptor tyrosine kinases, even in oncogenic KRAS backgrounds. Thus, rigorous identification of human cell line fitness genes using a high-complexity CRISPR-Cas9 library affords a high-resolution view of the genetic vulnerabilities of a cell.
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| 4. |
- Hudson, Lawrence N, et al.
(författare)
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The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
- 2017
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 7:1, s. 145-188
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Tidskriftsartikel (refereegranskat)abstract
- The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
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| 5. |
- Jonsson, Mats, et al.
(författare)
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Dissolution of UO2 by one- and two-electron oxidants
- 2004
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 807, s. 77-82
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the efficiency of one- and two-electron oxidants in oxidative dissolution Of UO2 has been investigated. This was accomplished by measuring the U(VI)-concentration in solution after exposing UO2-powder to controlled amounts of oxidants in aqueous solution. The oxidants used in this study are H2O2, IrCl62-, CO3.- and OH..H2O2 acts as a two-electron oxidant while the remaining three oxidants are one-electron oxidants. CO3.- and OH. were generated using gamma-radiolysis. The results clearly show that the dissolution yields for one-electron oxidants (per electron pair) are lower than the yields for two-electron oxidants. Furthermore, the yields for one-electron oxidants increase with increasing amount of oxidant (especially at low amounts of oxidant). The rationale for this is that U(VI) is the main soluble species which is formed directly upon two-electron oxidation. For one-electron oxidants the primary oxidation product is U(V) which can form U(VI) upon reaction with a second oxidant. The probability for a second oxidation is however low at low concentrations of oxidant.
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| 6. |
- Jonsson, Mats, et al.
(författare)
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Radiation induced spent nuclear fuel dissolution under deep repository conditions
- 2007
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 41:20, s. 7087-7093
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of spent nuclear fuel dissolution in groundwater is an important part of the safety assessment of a deep geological repository for high level nuclear waste. In this paper we discuss the most important elementary processes and parameters involved in radiation induced oxidative dissolution of spent nuclear fuel. Based on these processes, we also present a new approach for simulation of spent nuclear fuel dissolution under deep repository conditions. This approach accounts for the effects of fuel age, burn up, noble metal nanoparticle contents, aqueous H-2 and HCO3- concentration, water chemistry, and combinations thereof. The results clearly indicate that solutes consuming H2O2 and combined effects of noble metal nanoparticles and H-2 have significant impact on the rate of spent nuclear fuel dissolution. Using data from the two possible repository sites in Sweden, we have employed the new approach to estimate the maximum rate of spent nuclear fuel dissolution. This estimate indicates that H-2 produced from radiolysis of groundwater alone will be sufficient to inhibit the dissolution, completely for spent nuclear fuel older than 100 years.
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| 7. |
- Knutsen, Halvor, et al.
(författare)
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Combining population genomics with demographic analyses highlights habitat patchiness and larval dispersal as determinants of connectivity in coastal fish species
- 2022
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 31:9, s. 2562-2577
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Tidskriftsartikel (refereegranskat)abstract
- Gene flow shapes spatial genetic structure and the potential for local adaptation. Among marine animals with non-migratory adults, the presence or absence of a pelagic larval stage is thought to be a key determinant in shaping gene flow and the genetic structure of populations. In addition, the spatial distribution of suitable habitats is expected to influence the distribution of biological populations and their connectivity patterns. We used whole genome sequencing to study demographic history and reduced representation (ddRAD) sequencing data to analyze spatial genetic structure in broadnosed pipefish (Syngnathus typhle). Its main habitat is eelgrass beds, which are patchily distributed along the study area in southern Norway. Demographic connectivity among populations was inferred from long-term (~30 year) population counts that uncovered a rapid decline in spatial correlations in abundance with distance as short as ~2 km. These findings were contrasted with data for two other fish species that have a pelagic larval stage (corkwing wrasse, Symphodus melops; black goby, Gobius niger). For these latter species, we found wider spatial scales of connectivity and weaker genetic isolation-by-distance patterns, except where both species experienced a strong barrier to gene flow, seemingly due to lack of suitable habitat. Our findings verify expectations that a fragmented habitat and absence of a pelagic larval stage promote genetic structure, while presence of a pelagic larvae stage increases demographic connectivity and gene flow, except perhaps over extensive habitat gaps.
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| 8. |
- Landis, Susanne H., et al.
(författare)
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Behavioral adjustments of a pipefish to bacterial Vibrio challenge
- 2012
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 66:10, s. 1399-1405
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Tidskriftsartikel (refereegranskat)abstract
- Animals can profit from increasing temperatures by prolonged breeding seasons and faster growth rates. However, these fitness benefits are traded off against higher parasite load and increased virulence of temperature-sensitive pathogens. In thermally stratified habitats, behavioral plasticity can allow hosts to choose the optimal temperature to enhance individual fitness and to escape parasite pressure. To test this idea, we performed a temperature choice experiment with the host-parasite system of the sex-role reversed broad-nosed pipefish (Syngnathus typhle) and its bacterial pathogen Vibrio spp. In this species, pregnant males are expected to face a trade-off between shortening their brooding period in warm water and decreasing the effect of the infection in cold water. We found that exposure to Vibrio changed the temperature preference for both pregnant and nonpregnant males, as well as females compared to nonchallenged fish that tended to prefer warm water. This study shows that behavioral plasticity is one option for avoidance of higher bacterial prevalence, as expected due to rising ocean temperatures.
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| 9. |
- Landis, Susanne H., et al.
(författare)
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Female pipefish can detect the immune status of their mates
- 2015
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 69:12, s. 1917-1923
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Tidskriftsartikel (refereegranskat)abstract
- Given the ubiquity of the parasites and their important fitness consequences on mate and offspring condition, selection for the ability to distinguish healthy from parasitized potential mates is a key process to enhance Darwinian fitness. In this study, we experimentally evaluated how the immunological experience of two potential partners influences mate choice, using the sex-role-reversed pipefish Syngnathus typhle. We exposed S. typhle to immune challenges with heat-killed Vibrio bacteria and investigated whether the activation of the immune system determined mate preferences. Our results demonstrate that the immune status of the potential partners influenced female mate preference, such that females that were exposed to an immune challenge became choosy and favored unchallenged males. Males, however, did not show any preferences for female immune status. In this context, we discuss mate choice decisions and behavioral plasticity as a complex result of immune challenge, severity of infection, as well as trans-generational effects.
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| 10. |
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