| 1. |
- Fors, Dan, 1982, et al.
(författare)
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Theoretical investigation of moderate misfit and interface energetics in the Fe/VN system
- 2010
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Ingår i: Computational Materials Science. - : Elsevier BV. - 0927-0256. ; 50:2, s. 550-559
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Tidskriftsartikel (refereegranskat)abstract
- In this study an ab initio based approach to determine the effect of moderate misfit on energies and structures for interfaces is presented and applied to the Fe(0 0 1)/VN(0 0 1) system. The interface energetics of the coherent and semicoherent structures of thin VN films in Fe is investigated in order to determine how the misfit is taken up. The coherent interface is directly treated with ab initio calculations, whereas the semicoherent interface energy is accessed by using a Peierls-Nabarro framework, in which ab initio data for chemical interactions across the interface is combined with a continuum description to account for the elastic distortions. The continuum treatment is here extended to thoroughly account for the anisotropy in the materials. Our approach shows that the elastic contribution to the total interface energy dominates for both the coherent and semicoherent structure and must therefore be accurately accounted for in the interface description. Further, the Peierls-Nabarro framework for the semicoherent interface is evaluated by comparing a full scale two-dimensional solution to one-dimensional approximations. We show that the one-dimensional treatment is sufficient in the present case for accurate results, and consequently interactions at dislocation intersections at the interface do not have to be considered. © 2010 Elsevier B.V. All rights reserved.
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| 2. |
- Johansson, Sven, 1981, et al.
(författare)
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A computational study of special grain boundaries in WC–Co cemented carbides
- 2015
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Ingår i: Computational Materials Science. - : Elsevier BV. - 0927-0256. ; 98, s. 345-353
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we model Sigma = 2 and Sigma = 1 {10 (1) over bar0}parallel to{10 (1) over bar0} WC/WC boundaries in WC-Co using density functional theory (DFT). In particular, the misfit structure of the Sigma = 2 twist boundary is modeled explicitly with a previously developed Peierls-Nabarro model for misfit dislocations. The grain boundary energy of the twist boundary is found to be 0.7 J/m(2), which is small in comparison with energies of general WC/WC boundaries. The misfit structure can be described as a square network of screw dislocations with Burgers vectors 1/6 . Our calculations show that Co will not segregate to the Sigma = 2 twist boundary, which contrasts with predictions for other WC/WC boundaries that typically give half a monolayer of segregated Co.
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| 3. |
- Petisme, Martin, 1981, et al.
(författare)
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A computational study of interfaces in WC-Co cemented carbides
- 2015
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Ingår i: Modelling and Simulation in Materials Science and Engineering. - : IOP Publishing. - 1361-651X .- 0965-0393. ; 23:4, s. 045001-
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Tidskriftsartikel (refereegranskat)abstract
- Interfaces in WC-Co cemented carbides have been investigated using the density functional theory (DFT). Six different model WC/WC grain boundaries are considered, together with the corresponding WC surfaces and WC/Co phase boundaries. The contribution to the grain boundary energies arising from misfit is estimated using an analytical bond order potential (ABOP) and the effect of magnetism is investigated using spinpolarized and non-spinpolarized calculations. A systematic study of adsorption of Co to WC surfaces, Co segregation to WC/WC grain boundaries and Co substitution at WC/Co phase boundaries has been carried out. Adsorption of Co to most WC surfaces is predicted, and result in a monolayer coverage of Co and sometimes a mixed Co/W or Co/W monolayer. The WC surfaces will become prewetted with Co as soon as the atoms become mobile at finite temperatures. Co substitutional segregation is predicted to all model WC/WC grain boundaries in 0.5 monolayer proportion. The segregation of Co to grain boundaries stabilizes the continuous skeleton network of hard WC grains in cemented carbides. Using the obtained interfacial energies, the wetting and the driving force for cobalt grain boundary infiltration are discussed. A dependence on the wetting efficiency on the carbon chemical potential is predicted, which could be an explanation for the better wetting observed experimentally under W-rich conditions.
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| 4. |
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| 5. |
- Boström, Pontus, 1982, et al.
(författare)
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SNARE proteins mediate fusion between cytosolic lipid droplets and are implicated in insulin sensitivity.
- 2007
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Ingår i: Nature cell biology. - : Springer Science and Business Media LLC. - 1465-7392 .- 1476-4679. ; 9:11, s. 1286-93
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Tidskriftsartikel (refereegranskat)abstract
- The accumulation of cytosolic lipid droplets in muscle and liver cells has been linked to the development of insulin resistance and type 2 diabetes. Such droplets are formed as small structures that increase in size through fusion, a process that is dependent on intact microtubules and the motor protein dynein. Approximately 15% of all droplets are involved in fusion processes at a given time. Here, we show that lipid droplets are associated with proteins involved in fusion processes in the cell: NSF (N-ethylmaleimide-sensitive-factor), alpha-SNAP (soluble NSF attachment protein) and the SNAREs (SNAP receptors), SNAP23 (synaptosomal-associated protein of 23 kDa), syntaxin-5 and VAMP4 (vesicle-associated membrane protein 4). Knockdown of the genes for SNAP23, syntaxin-5 or VAMP4, or microinjection of a dominant-negative mutant of alpha-SNAP, decreases the rate of fusion and the size of the lipid droplets. Thus, the SNARE system seems to have an important role in lipid droplet fusion. We also show that oleic acid treatment decreases the insulin sensitivity of heart muscle cells, and this sensitivity is completely restored by transfection with SNAP23. Thus, SNAP23 might be a link between insulin sensitivity and the inflow of fatty acids to the cell.
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| 6. |
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| 7. |
- Johansson, Sven, 1981
(författare)
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A computational study of interface structures and energetics in cemented carbides and steels
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cemented carbides are hard composite materials of great industrial importance. Because of their combination of hardness and toughness, they are used e.~g. for cutting, drilling, turning and milling. The material is produced by means of powder metallurgy, where powders of carbide and metal are sintered together into a hard and dense material. To retain a fine WC-Co microstructure, additions of VC, Cr3C2, TiC etc. are often made to inhibit WC grain growth.In this thesis, a computational study of interface structures and energetics in WC-Co cemented carbides is presented. The investigation is performed in the density functional theory framework with a plane-wave pseudopotential method. To make predictions of interface energies, coherent atomic interface configurations are used.We have calculated the stability of thin layers of cubic TiC, VC, CrC, NbC, MoC, HfC and TaC in the interface between WC and Co. Due to a lowering of the WC/Co interface energy, we predict that thin VC films of two atomic layers are stable at the basal WC/Co interfaces at high temperature sintering conditions under which grain growth occurs. The predicted atomic structure is in agreement with available high-resolution electron microscopy images. A comparison between the stability of various carbide films in both basal and prismatic WC/Co interfaces provides a consistent explanation for the experimentally known effectiveness of VC as grain growth inhibitor.Furthermore, we have extended our modeling of interfaces to include the effect of misfit in semicoherent interfaces. Information of interface energetics from atomistic simulation is coupled to a continuum model of elasticity in the Peierls-Nabarro scheme to account for misfit dislocations. The method is applied to the low misfit Fe/VN interface in steels, and we find that its interface energy is dominated by elastic energy.
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| 8. |
- Johansson, Sven, 1981, et al.
(författare)
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A computational study of thin cubic carbide films in WC/Co interfaces
- 2011
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454. ; 59:1, s. 171-181
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Tidskriftsartikel (refereegranskat)abstract
- We examine the propensity for the formation of thin films of cubic TiC, VC, CrC, ZrC, NbC, MoC, HfC, TaC and WC in the metal ceramic interface between simple hexagonal WC and Co using density functional theory Films of TiC, VC, CrC and MoC are predicted to be stable, of which VC and MoC show the strongest propensity for formation The results provide an explanation for the experimen tally observed WC grain growth inhibition effect and alteration of WC grain shape attained in VC-doped WC Co.
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| 9. |
- Johansson, Sven, 1981, et al.
(författare)
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First-principles derived complexion diagrams for phase boundaries in doped cemented carbides
- 2016
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Ingår i: Current Opinion in Solid State and Materials Science. - : Elsevier BV. - 1359-0286. ; 20:5, s. 299-307
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Forskningsöversikt (refereegranskat)abstract
- This article reviews a method for calculating an equilibrium interfacial phase diagram depicting regions of stability for different interface structures as function of temperature and chemical potentials. Density functional theory (DFT) is used for interfacial energies, Monte Carlo simulations together with cluster expansions based on DFT results for obtaining configurational free energies, and CALPHAD-type modeling for describing the thermodynamic properties of the adjoining bulk phases. An explicit case, vanadium doped cemented carbides, is chosen to illustrate the progress in the research field and the interfacial diagram, a complexion diagram, for the phase boundary WC(0001)/Co is constructed as function of temperature and chemical potentials.
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| 10. |
- Johansson, Sven, 1981, et al.
(författare)
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First-principles study of an interfacial phase diagram in the V-doped WC-Co system
- 2012
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 86:3, s. 035403-
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Tidskriftsartikel (refereegranskat)abstract
- We present a method of determining an interfacial phase diagram using density functional theory calculations for interface energetics. Cluster expansions based on these calculations are used in Monte Carlo simulations to obtain configurational free energies. The method is applied to study the segregation of V to the WC(0001)/Co interface and to construct the corresponding interface diagram, a "complexion" phase diagram. By CALPHAD-type analysis for the adjoining bulk phases, a connection with real materials is made. We find that, in equilibrium, the interface contains a thin V-rich film for a wide range of temperatures and chemical potentials of V corresponding to V additions below the (V, W)C-x solubility limit. The results are compared with available experimental data, and implications of the strong segregation of V for the sintering process of V-doped WC-Co are discussed.
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| 11. |
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| 12. |
- Johansson, Sven, 1981
(författare)
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Multiscale Modeling of Interfaces
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Understanding strength and stability of interfaces between dissimilar materials or phases is a highly active field of contemporary materials research. Knowledge of interface structure and energetics is important for modeling of complex materials both on a mechanical and thermodynamical level as well as for many functional properties. Interfaces is a collective term including surfaces, interphase boundaries and grain boundaries. A general interface can be sharp or diffuse, planar or corrugated. The interface between two crystals is usually quite sharp, and can be classified as coherent, semicoherent or incoherent depending on the mismatch between the adjoining crystals.The goal of this Thesis is to obtain a better understanding of interfacial structures and energetics, in particular of semicoherent interfaces. Previous first-principles work in the field has often excluded the effect of misfit. Therefore, we present a simple model combining the interfacial interaction from first-principles methods with a continuum description to account for the elastic displacements. The accuracy of the model has been satisfactorily tested against atomistic modelling.We investigate the effect of misfit on interfaces in two classes of materials: steels and cemented carbides. In the first case, we study the interface between Fe and a VN precipitate. The results show that even a small misfit (2%) has a large influence on the interface energy. In the second case, we apply the method to the semicoherent Sigma=2 twist boundary found in both tungsten carbide powder and sintered cemented carbides. The results are discussed in the context of grain boundary evolution during sintering.
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| 13. |
- Johansson, Sven, 1981, et al.
(författare)
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Theory of ultrathin films at metal-ceramic interfaces
- 2010
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Ingår i: Philosophical Magazine Letters. - : Informa UK Limited. - 0950-0839 .- 1362-3036. ; 90:8, s. 599-609
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical model for understanding the formation of interfacial thin films is presented, which combines density functional theory calculations for interface energies with thermodynamic modeling techniques for multicomponent bulk systems. The theory is applied to thin film formation in VC-doped WC-Co cemented carbides. It is predicted that ultrathin VC films may exist in WC/Co interfaces at the high temperature sintering conditions where most of the WC grain growth occurs, which provides an explanation of the grain growth inhibiting effect of VC additions in the WC-Co system.
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| 14. |
- Lay, S., et al.
(författare)
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Interface structure in a WC-Co alloy co-doped with VC and Cr3C2
- 2012
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 47:3, s. 1588-1593
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Tidskriftsartikel (refereegranskat)abstract
- The effect of carbide additions is investigated at the atom scale by studying the interface between the cubic carbide phase and the WC prismatic facet in a VC Cr 3 C 2 co-doped WC Co alloy using high-resolution transmission electron microscopy. The alloy was prepared from WC powder about 0.5 lm in size and sintered at 1400°C for 2 h. The orientation relationship between WC and the MC carbide at the prismatic facet of WC is the same orientation as the one found at a WC/(Cr, W)C interface in Cr 3 C 2 -doped alloys. the image of WC shows triangular patterns indicating the position of the C atomic columns in this crystal. In MC crystal, some elongation of the bright areas parallel to the interface is observed on the simulation. The presence of dislocations at interfaces can be related to the parametric mismatch between the two neighboring crystals, to the presence of different stable structural units, or to an angular deviation between the crystals.
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| 15. |
- Nordin, Elise, 1985, et al.
(författare)
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An inverse association between plasma benzoxazinoid metabolites and PSA after rye intake in men with prostate cancer revealed with a new method
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Prostate cancer (PC) is a common cancer among men, and preventive strategies are warranted. Benzoxazinoids (BXs) in rye have shown potential against PC in vitro but human studies are lacking. The aim was to establish a quantitative method for analysis of BXs and investigate their plasma levels after a whole grain/bran rye vs refined wheat intervention, as well as exploring their association with PSA, in men with PC. A quantitative method for analysis of 22 BXs, including novel metabolites identified by mass spectrometry and NMR, was established, and applied to plasma samples from a randomized crossover study where patients with indolent PC (n = 17) consumed 485 g whole grain rye/rye bran or fiber supplemented refined wheat daily for 6 wk. Most BXs were significantly higher in plasma after rye (0.3–19.4 nmol/L in plasma) vs. refined wheat (0.05–2.9 nmol/L) intake. HBOA-glc, 2-HHPAA, HBOA-glcA, 2-HPAA-glcA were inversely correlated to PSA in plasma (p < 0.04). To conclude, BXs in plasma, including metabolites not previously analyzed, were quantified. BX metabolites were significantly higher after rye vs refined wheat consumption. Four BX-related metabolites were inversely associated with PSA, which merits further investigation.
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| 16. |
- Sattler, Florian, et al.
(författare)
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Lifting inter-app data-flow analysis to large app sets
- 2018
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Ingår i: Automated Software Engineering : An International Journal. - : Springer Science and Business Media LLC. - 0928-8910. ; 25:2, s. 315-346
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Tidskriftsartikel (refereegranskat)abstract
- LLC Mobile apps process increasing amounts of private data, giving rise to privacy concerns. Such concerns do not arise only from single apps, which might—accidentally or intentionally—leak private information to untrusted parties, but also from multiple apps communicating with each other. Certain combinations of apps can create critical data flows not detectable by analyzing single apps individually. While sophisticated tools exist to analyze data flows inside and across apps, none of these scale to large numbers of apps, given the combinatorial explosion of possible (inter-app) data flows. We present a scalable approach to analyze data flows across Android apps. At the heart of our approach is a graph-based data structure that represents inter-app flows efficiently. Following ideas from product-line analysis, the data structure exploits redundancies among flows and thereby tames the combinatorial explosion. Instead of focusing on specific installations of app sets on mobile devices, we lift traditional data-flow analysis approaches to analyze and represent data flows of all possible combinations of apps. We developed the tool Sifta and applied it to several existing app benchmarks and real-world app sets, demonstrating its scalability and accuracy.
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| 17. |
- Sellstedt, Magnus, 1981-, et al.
(författare)
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Synthesis and Characterization of a Multi Ring-Fused 2-Pyridone-Based Fluorescent Scaffold
- 2010
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1434-193X .- 1099-0690. ; :32, s. 6171-6178
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Tidskriftsartikel (refereegranskat)abstract
- A series of compounds based on a novel fluorescent scaffold have been synthesized. Most of the compounds displayed high quantum yields of fluorescence and unusually long fluorescence lifetimes. HeLa cells were treated with one of the compounds and its use as a fluorescent dye was demonstrated with fluorescence confocal microscopy.
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| 18. |
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| 19. |
- Weidow, Jonathan, 1980, et al.
(författare)
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Transition Metal Solubilities in WC in Cemented Carbide Materials
- 2011
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Ingår i: Journal of the American Ceramic Society. - : Wiley. - 0002-7820 .- 1551-2916. ; 94:2, s. 605-610
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Tidskriftsartikel (refereegranskat)abstract
- Solubilities of different transition metals in WC in cemented carbides at around 1700 K were determined with atom probe tomography. Ta had the highest solubility, followed by Nb, Cr, and V, all with atom fractions in the 10−3 range. Ti and Mn showed lower, yet detectable, solubilities in the 10−6 or 10−5 range. Zr and Co solubilities were too low to be measured. The results were compared with the theoretically calculated solubilities using density functional theory. These calculations predicted that Ta, Nb, V, and Cr should have the highest solubility, all in the 10−4 or 10−3 range. Ti was predicted to have a lower solubility (10−5 range) and Co, Hf, and Zr even lower (10−8 or 10−7 range).
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| 20. |
- Zamaratskaia, Galia, et al.
(författare)
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Consumption of whole grain/bran rye instead of refined wheat decrease concentrations of TNF-R2, e-selectin, and endostatin in an exploratory study in men with prostate cancer
- 2020
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Ingår i: Clinical Nutrition. - : Elsevier BV. - 1532-1983 .- 0261-5614. ; 39:1, s. 159-165
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Tidskriftsartikel (refereegranskat)abstract
- Background & aims: Rye consumption has shown beneficial effects on prostate cancer tumors, as indicated by slower initial tumor growth in animal models and lowering of prostate-specific antigen (PSA) in humans. This study evaluated the effects of whole grain/bran rye consumption on low-grade inflammation and endothelial function biomarkers in men with prostate cancer. Methods: Seventeen men with untreated, low-grade prostate cancer consumed 485 g rye whole grain and bran products (RP) per day or refined wheat products with added cellulose (WP) in a randomized crossover design. Fasting blood samples were taken before and after 2, 4, and 6 weeks of treatment. Results: Concentrations of tumor nuclear factor-receptor 2 (TNF-R2), e-selectin, and endostatin were significantly lower after consumption of the RP diet compared with WP (p < 0.05). Cathepsin S concentration was positively correlated to TNF-R2 and endostatin concentrations across all occasions. Strong correlations were consistently found between intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and between interleukin-6 (IL-6) and interleukin-1 receptor antagonist (IL-1RA). No effect of intervention was found in 92 inflammation-related protein biomarkers measured in a proximity extension assay. Conclusions: RP diet lowered TNF-R2, e-selectin, and endostatin, compared with WP in men with prostate cancer. These effects were accompanied by a reduction in PSA.
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