| 1. |
- Andersen, Kim, et al.
(författare)
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Maintenance and Reformation of News Repertoires: A Latent Transition Analysis
- 2022
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Ingår i: Journalism & Mass Communication Quarterly. - : SAGE Publications. - 1077-6990 .- 2161-430X. ; 99:1
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Tidskriftsartikel (refereegranskat)abstract
- Today’s media environment provides people ample opportunities for constructing news habits fitting their preferences, but our knowledge about the dynamics of such news habits is limited. Using a four-wave panel survey from Sweden and taking a news repertoires approach, the study identifies four groups of news users labeled Public service-oriented traditionalists, Minimalists, Engaged pluralists, and Quality-oriented explorers, which are each related to news interest, trust in mainstream news media, and socio-demographic factors in distinct ways. The news repertoires are highly stable, even during profound contextual change, showing that people most often maintain their news habits and only seldom reform them.
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| 2. |
- Johansson, Adam Johannes, et al.
(författare)
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Insights from post-test examination of three packages from the MiniCan test series of copper-cast iron canisters for geological disposal of spent nuclear fuel : impact of the presence and density of bentonite clay
- 2017
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Ingår i: Corrosion Engineering, Science and Technology. - 1478-422X .- 1743-2782. ; 52, s. 54-60
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Tidskriftsartikel (refereegranskat)abstract
- MiniCan is a field test designed to highlight certain aspects of corrosion in a KBS-3 type repository for spent nuclear fuel. Five experimental packages containing miniature copper-cast iron canisters were installed in the Äspö Hard Rock Laboratory in 2006. Three packages have been retrieved, MiniCan 3 in 2011 and MiniCan 4 and 5 in 2015. The packages were examined regarding surface chemistry, microbiology and corrosion of copper and iron. The main difference in design between the retrieved packages was the presence and density of bentonite clay. Black deposits of sulphides were visually noted during dismantling of both MiniCan 3 (low density clay) and MiniCan 5 (no clay), but not in MiniCan 4 (high density clay). Extensive corrosion of cast iron specimens was observed in all three packages, with local attacks corresponding to the loss of hundreds of µm/y. Sulphate reducing bacteria (SRB) were found to be present in ground water, in bentonite clay and on surfaces of various specimens of iron and copper, and it is suggested that the SRB activity had a pronounced influence on the corrosion observed. Copper surfaces display a roughness at the µm level and the integrated corrosion rate of copper mass-loss specimens was generally low. This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems. © 2017 The Author(s).
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| 3. |
- Shehata, Adam, 1981, et al.
(författare)
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Climate Change Frame Acceptance and Resistance: Extreme Weather, Consonant News, and Personal Media Orientations
- 2022
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Ingår i: Mass Communication & Society. - : Informa UK Limited. - 1520-5436 .- 1532-7825. ; 25:1, s. 51-76
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Tidskriftsartikel (refereegranskat)abstract
- Across the globe, extreme weather events have brought climate change into people’s daily lives. Extended heatwaves, droughts, and wildfires are now recurring in many regions across the globe. This study asks how the exceptional 2018 summer influenced climate change beliefs among Swedish citizens. More specifically, the study looks deeper into belief formation dynamics under intense, consonant, and extended news reporting–addressing one of the most fundamental media effects in the literature: the over-time maintenance of societal beliefs through cumulative and repetitive exposure to a dominant issue frame. Using a unique three-wave panel survey, the analysis focuses on citizens’ acceptance (and resistance) of the dominant climate change frame provided by traditional media–whether citizens believe in the existence, causes, and consequences of climate change. The findings reveal strong support for belief maintenance effects over time, but also that belief changes are possible. Even in situations of intense and consonant news reporting, acceptance (and resistance) of the dominant climate change frame depends on citizens’ personal media orientations. Both trust in traditional news media and usage of alternative online news emerge as key factors conditioning classic media effects in a fragmented and polarized media environment.
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| 4. |
- Blomberg, Margareta R. A., et al.
(författare)
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O-O bond cleavage in dinuclear peroxo complexes of iron porphyrins : a quantum chemical study
- 2007
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 46:19, s. 7992-7997
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Tidskriftsartikel (refereegranskat)abstract
- To gain insight into the mechanisms of O-2 activation and cleavage in metalloenzymes, biomimetic metal complexes have been constructed and experimentally characterized. One such model complex is the dinuclear peroxo complex of iron porphyrins observed at low temperature in a noncoordinating solvent. The present theoretical study examines the O-O bond cleavage in these complexes, experimentally observed to occur either at increased temperature or when a strongly coordinating base is added. Using hybrid density functional theory, it is shown that the O-O bond cleavage always occurs in a state where two low-spin irons (S = +/- 1/2) are antiferromagnetically coupled to a diamagnetic state. This state is the ground state when the strong base is present and forms an axial ligand to the free iron positions. In contrast, without the axial ligands, the ground state of the clinuclear peroxo complex has two high-spin irons (S = +/- 5/2) coupled antiferromagnetically. Thus, the activation barrier for O-O bond cleavage is higher without the base because it includes also the promotion energy from the ground state to the reacting state. It is further found that this excitation energy, going from 10 unpaired electrons in the high-spin case to 2 in the low-spin case, is unusually difficult to determine accurately from density functional theory because it is extremely sensitive to the amount of exact exchange included in the functional.
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| 5. |
- Halldin Stenlid, Joakim, et al.
(författare)
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Aqueous Solvation and Surface Oxidation of the Cu7 Nanoparticle : Insights from Theoretical Modeling
- 2016
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:3, s. 1977-1988
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Tidskriftsartikel (refereegranskat)abstract
- The current understanding on: the behavior of nano particles in solution is limited. We have studied tho effects of the aqueous environment on the anoxic oxidation of a Cu-7 riannpartide using a range of different computational solvation models. On the basis of a series of hydroxylated Cu-7(H2O)(y)(OH)x structures, the performance of standard continuum models have been compared to discrete models including up to, and beyond, the second solvation layer. Both full quantum chemical 4 (DFT: PBEO-D3) and QM/MM (PBEO/EPP1) computations were employed in the analysis. The Cu-7 structures were solvated in water nanodroplets and studied by molecular dynamics simulations. On the basis of the simulations, we were able to identify new modes of H2O interactions with the Cu(7)particle, modes that were previously considered unbeneficial. All solvation models favor the "Same equilibrium oxidation state corresponding to a Cu(I)OH surface species. However, for quantitative energy comparison of similar- systems, our results suggest the use of a combined water cinst07cniftinuum model including at least a first explicit solvation shell for energetic comparisons. Nevertheless, the second solvatiOn:thell is -important for identifying representative inner solvation shell structures.
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| 6. |
- Halldin Stenlid, Joakim, et al.
(författare)
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Computational Analysis of the Early Stage of Cuprous Oxide Sulphidation : A Top-Down Process
- 2017
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Ingår i: Corrosion Engineering, Science and Technology. - 1478-422X .- 1743-2782. ; 52:S1, s. 50-53
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Tidskriftsartikel (refereegranskat)abstract
- The initial steps of Cu2O sulphidation to Cu2S have been studied using plane-wave density functional theory at the PBE-D3+U level of sophistication. Surface adsorption and dissociation of H2S and H2O, as well as the replacement reaction of lattice oxygen with sulphur, have been investigated for the most stable (111) and (100) surface facets under oxygen-lean conditions. We find that the (100) surface is more susceptible to sulphidation than the (111) surface, promoting both H2S adsorption, dissociation and the continued oxygen–sulphur replacement. The results presented in this proceeding bridge previous results from high-vacuum experiments on ideal surface to more realistic corrosion conditions and set the grounds for future mechanistic studies. Potential implications on the long-term final disposal of spent nuclear fuel are discussed.
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| 7. |
- Halldin Stenlid, Joakim, et al.
(författare)
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Electrochemical Interface during Corrosion of Copper in Anoxic Sulfide-Containing Groundwater-A Computational Study
- 2020
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 124:1, s. 469-481
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Tidskriftsartikel (refereegranskat)abstract
- Corrosion of copper is an expensive degradation process of materials in engineered infrastructures and in various technical applications. It is also an important factor in the geological disposal of spent nuclear fuel, where sulfide-induced corrosion is expected to be the predominant chemical degradation process of copper canisters used for encapsulation and isolation of the radioactive material from the biosphere. One aspect of the corrosion process that is still under intense research is the corrosion morphology and how it might be affected by the composition of the groundwater. Using density functional theory, we investigate the electrochemical interface of corroding copper in aqueous solutions containing sulfides, with and without the presence of Cl-, HCO3-, and SO42- anions. Through state-of-the-art electrochemical models, we account for the effects of pH, concentrations, and potential on the interfacial structure and composition. Results are presented for the Cu(110) surface facet and compared to the (110) and (001) facets of chalcocite (Cu2S), i.e., the main product of sulfide-induced corrosion. It is found that at low potentials, H dominates on all surfaces, and at high potentials, sulfides. In the intermediate ranges, the surfaces differ with sulfides prevailing on Cu, while adsorbed H2O, Cl, or H dominate on Cu2S. The results are summarized as surface Pourbaix diagrams and are generally applicable in corrosion science and electrochemistry. The implications of the study are discussed in light of the expected conditions of planned spent nuclear fuel repositories in Sweden, Finland, and Canada.
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| 8. |
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| 9. |
- Halldin Stenlid, Joakim, et al.
(författare)
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On the Nature of the Cathodic Reaction during Corrosion of Copper in Anoxic Sulfide Solutions
- 2019
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 166:6, s. C196-C208
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Tidskriftsartikel (refereegranskat)abstract
- Sulfide-induced corrosion is expected to be the dominating long-term corrosion process for copper containers in technical concepts for deep geological disposal of spent nuclear fuel (SNF), adapted in several waste management programs around the world. The present study investigates the atomic-scale mechanism of the cathode side of the corrosion reaction using Density Functional Theory (DFT) calculations. Despite the central role of the reaction, neither the site of reaction nor the active species has been previously established. Here we compare the cathodic reaction leading to H-2-evolution on pure copper and on chalcocite (Cu2S) surfaces. The considered H-donors are OH-/H2O and HS-/H2S which are all available at the neutral to alkaline conditions anticipated at the SNF disposal sites. Assuming Volmer-Tafel-Heyrovsky kinetics, we find that the cathodic reactions are many orders of magnitude faster on copper compared to copper sulfide. Although we find that HS-/H2S have lower reaction barriers than H2O, our kinetic analysis suggest that H2O is expected to be the main H-source for the cathodic reaction under SNF repository conditions as results of the low sulfide concentrations (less than or similar to 10 mu M) expected in SNF repositories in Sweden, Finland and Canada.
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| 10. |
- Halldin Stenlid, Joakim, et al.
(författare)
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Properties of interfaces between copper and copper sulphide/oxide films
- 2021
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 183
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Tidskriftsartikel (refereegranskat)abstract
- We compare different means of predicting and rationalizing properties of corrosion films aiming at gaining deeper understanding of the behaviour of copper in aqueous and sulphide-containing environments. Purely geometrical tools ranging from mean bulk information to anisotropic and facet-specific approaches are discussed, and their performances compared against DFT-based stability and property evaluations of a range of interfaces arising from combining low-index crystallographic planes of the compounds Cu, Cu2O, and Cu2S. We demonstrate the necessity to consider facet-specific interactions to understand nanolevel differences between Cu2S and Cu2O film behaviour, and that thin films cannot be directly described by bulk properties.
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