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| 2. |
- Bigdeli, Sedigheh, 1984, et al.
(författare)
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Strategies for High-Temperature Corrosion Simulations of Fe-Based Alloys Using the Calphad Approach : Part I
- 2021
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Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 42:3, s. 403-418
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Tidskriftsartikel (refereegranskat)abstract
- The environmental degradation of materials at high temperatures limits the useful life of different industrial components and hinders the development of more economical and environmentally friendly processes for the energy production. Despite the importance of this phenomena, a model to predict lifetime of materials that degrade due to high-temperature corrosion has up till now been lacking due to limitations of the computational possibilities and the complex nature of oxidation. In the present work we develop some strategies to model high-temperature corrosion in Fe-based alloys using the Calphad (Calculation of Phase Diagrams) approach. It is proposed that kinetic-based simulations for oxidation of Al and Cr can accurately represent the lifetime of the protective layers in FeCrAl and FeCr alloys at different temperatures in air. The oxide systems are in addition investigated by equilibrium calculations. The corrosion mechanisms of FeCr and FeCrAl alloys are discussed based on theoretical and experimental knowledge.
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| 3. |
- Bratberg, J., et al.
(författare)
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The Development and Validation of a New Thermodynamic Database for Ni-Based Alloys
- 2012
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Ingår i: Proceedings of the International Symposium on Superalloys 2012. - Hoboken, NJ, USA : John Wiley & Sons. - 9780470943205 ; , s. 803-812
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Konferensbidrag (refereegranskat)abstract
- Thermodynamic databases developed using the CALPHAD method has been successfully applied to the modeling and simulation of Ni based superalloys for more than fifteen years. Such databases when combined with suitable software, such as Thermo-Calc, can be used for accelerating alloy design as well as improving understanding of existing alloys in terms of their processing and in-service behavior. Additionally, such databases are also essential to the modeling of microstructural evolution using methods such as phase field or mean field approaches. A new thermodynamic database, TCNI6, has been developed for Ni-based superalloys based on the critical evaluation, using the CALPHAD method, of all the constituent binary systems across their full range of composition and many of the ternary systems containing Ni, as well as a number of other key ternary systems. The database has also been validated where possible against higher order systems as well. Together with the new mobility database, MOBNI3, which contains descriptions for the atomic mobility for respectively the γ (Al), γ' (Ll2), α (A2), β (B2) and liquid phases, TCNI6 can be used with software such as DICTRA to predict different kinetic aspects taking all relevant phases into account, e.g. the simulation of interdiffusion across Ni-based coatings. A new user friendly computational tool, TC-PRISMA, which simulates the kinetics of precipitation processes, is demonstrated utilizing these new databases and combined with interface property data. Engineering applications of precipitation modelling are validated against experimental data.
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| 5. |
- Dilner, David, et al.
(författare)
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Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems
- 2016
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Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer-Verlag New York. - 1547-7037 .- 1863-7345. ; , s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- Thermodynamic descriptions of the Fe-Mg-O, Fe-Ca-S and Fe-Mg-S systems are all important in order to perform thermodynamic calculations related to the steelmaking process. The experimental information of many sulphur-containing systems, including Fe-Ca-S and Fe-Mg-S, is lacking and they are here thus approximated to behave similarly to the corresponding oxygen systems. This study presents a description of the Fe-Mg-O system in good agreement with experimental information. Additionally, descriptions of the Fe-Ca-S and Fe-Mg-S systems are presented. These descriptions may be reasonable estimations considering the lack of experimental information.
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| 7. |
- Gertow, J., et al.
(författare)
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Ceramides are associated with inflammatory processes in human mediastinal adipose tissue
- 2014
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Ingår i: NMCD. Nutrition Metabolism and Cardiovascular Diseases. - : Elsevier BV. - 0939-4753 .- 1590-3729. ; 24:2, s. 124-131
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aim: Ceramides are poorly characterized in human adipose tissue. The aim of this study was to investigate concentrations of different ceramide species in human subcutaneous and visceral adipose tissue depots and to determine associations between ceramides and global gene expression profiles. Methods and Results: Concentrations of six ceramide species were determined in plasma and in subcutaneous and mediastinal adipose tissue from 10 overweight subjects (BMI 29.4±4.9kg/m2). In the adipose tissue biopsies gene expression arrays were performed and relationships between ceramides and gene expression analyzed. Immunostaining of the two adipose tissue depots was performed in an independent group of 10 patients. Mediastinal adipose tissue contained significantly higher concentrations (p<0.05) of all six ceramide species than the subcutaneous depot. Of the six ceramides in plasma, concentrations of only two (Cer d18:1/18:0 and Cer d18:1/22:0) correlated significantly (p<0.05) with the corresponding species in mediastinal adipose tissue, but there were no significant correlations between ceramides in plasma and subcutaneous adipose tissue. Multivariate analysis identified significant correlations between the total ceramide concentration and global gene expression within mediastinal, but not subcutaneous adipose tissue, according to cross-validation. Gene ontology analysis of genes related to ceramides in the mediastinal depot revealed that genes positively correlated with ceramides were associated mainly with immune and inflammatory categories, while genes negatively correlated with ceramides were associated mainly with lipid and carbohydrate metabolism. Conclusions: Ceramides in human mediastinal adipose tissue may be involved in inflammation and lipid and carbohydrate metabolism. © 2013 Elsevier B.V.
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| 9. |
- Maleki, S, et al.
(författare)
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Mesenchymal state of intimal cells may explain higher propensity to ascending aortic aneurysm in bicuspid aortic valves
- 2016
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6, s. 35712-
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Tidskriftsartikel (refereegranskat)abstract
- Individuals with a bicuspid aortic valve (BAV) are at significantly higher risk of developing aortic complications than individuals with tricuspid aortic valves (TAV) and defective signaling during the embryonic development and/or life time exposure to abnormal hemodynamic have been proposed as underlying factors. However, an explanation for the molecular mechanisms of aortopathy in BAV has not yet been provided. We combined proteomics, RNA analyses, immunohistochemistry, and electron microscopy to identify molecular differences in samples of non-dilated ascending aortas from BAV (N = 62) and TAV (N = 54) patients. Proteomic analysis was also performed for dilated aortas (N = 6 BAV and N = 5 TAV) to gain further insight into the aortopathy of BAV. Our results collectively showed the molecular signature of an endothelial/epithelial-mesenchymal (EndMT/EMT) transition-like process, associated with instability of intimal cell junctions and activation of RHOA pathway in the intima and media layers of ascending aorta in BAV patients. We propose that an improper regulation of EndMT/EMT during the spatiotemporally related embryogenesis of semilunar valves and ascending aorta in BAV individuals may result in aortic immaturity and instability prior to dilation. Exasperation of EndMT/EMT state in post embryonic life and/or exposure to non-physiological hemodynamic could lead to the aneurysm of ascending aorta in BAV individuals.
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