| 41. |
- Al-Zoubi, Noura, et al.
(författare)
-
Elastic properties of 4d transition metal alloys : Values and trends
- 2019
-
Ingår i: Computational materials science. - : ELSEVIER SCIENCE BV. - 0927-0256 .- 1879-0801. ; 159, s. 273-280
-
Tidskriftsartikel (refereegranskat)abstract
- Using the Exact Muffin-Tin Orbitals method within the Perdew-Burke-Ernzerhof exchange-correlation approximation for solids and solid surfaces (PBEso1), we study the single crystal elastic constants of 4d transition metals (atomic number Z between 39 and 47) and their binary alloys in the body centered cubic (bcc) and face centered cubic (fcc) structures. Alloys between the first neighbors Z(Z + 1) and between the second neighbors Z(Z + 2) are considered. The lattice constants, bulk moduli and elastic constants are found in good agreement with the available experimental and theoretical data. It is shown that the correlation between the relative tetragonal shear elastic constant C-fcc'-2C(bcc)' and the structural energy difference between the fcc and bcc lattices Delta E is superior to the previously considered models. For a given crystal structure, the equiatomic Z(Z + 2) alloys turn out to have similar structural and elastic properties as the pure elements with atomic number (Z + 1). Furthermore, alloys with composition Z(1-x)(Z + 2)(x) possess similar properties as Z(1-2x)(Z + 1)(2x). The present theoretical data on the structural and the elastic properties of 4d transition metal alloys provides consistent input for coarse scale modeling of material properties.
|
|
| 42. |
- Al-Zoubi, Noura, et al.
(författare)
-
Influence of Magnesium on hydrogenated ScAl1-xMgx alloys : a theoretical study
- 2011
-
Ingår i: Computational materials science. - : Elsevier BV. - 0927-0256 .- 1879-0801. ; 50:10, s. 2848-2853
-
Tidskriftsartikel (refereegranskat)abstract
- Ab initio total energy calculations, based on the projector augmented wave method and the exact mu±n-tin orbitals method in combination with the coherent-potential approximation, are used to examine the effect of magnesium on hydrogen absorption/desorption temperature and phase stability of hydrogenated ScAl1-xMgx (0 ≤ x ≤ 0:3) alloys. According to the experiments, ScAl1-xMgx adopts the CsCl structure, and upon hydrogen absorption it decomposes into ScH2 with CaF2 structure and Al-Mg with face centered cubic structure. Here we demonstrate that the stability field of the hydrogenated alloys depends sensitively on Mg content and on the microstructure of the decomposed system. For a given microstructure, the critical temperature for hydrogen absorption/desorption increases with Mg concentration.
|
|
| 43. |
- Al-Zoubi, Noura, et al.
(författare)
-
Influence of manganese on the bulk properties of Fe-Cr-Mn alloys : a first-principles study
- 2014
-
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 89:12, s. 125702-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of manganese on lattice stability and magnetic moments of paramagnetic Fe-Cr-Mn steel alloys along the Bain path connecting the body-centered cubic (bcc) and face-centered cubic (fcc) structures. The calculations are carried out using the ab initio exact muffin-tin orbital method, in combination with the coherent potential approximation, and the paramagnetic phase is modeled by the disordered local magnetic moment scheme. For all Fe-Cr-Mn alloys considered here, the local magnetic moments on Fe atoms have the minimum values for the fcc structure and the maximum values for the bcc structure, whereas the local magnetic moments on Mn have almost the same value along the constant-volume Bain path. Our results show that Mn addition to paramagnetic Fe-Cr solid solution stabilizes the bcc structure. However, when considering the paramagnetic fcc phase relative to the ferromagnetic bcc ground state, then Mn turns out to be a clear fcc stabilizer, in line with observations.
|
|
| 44. |
- Al-Zoubi, Noura, et al.
(författare)
-
Tetragonality of carbon-doped ferromagnetic iron alloys : A first-principles study
- 2012
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 85:1, s. 014112-
-
Tidskriftsartikel (refereegranskat)abstract
- Using density-functional theory in combination with the exact muffin-tin orbital (EMTO) method and coherent potential approximation, we investigate the alloying effect on the tetragonality of Fe-C solid solution forming the basis of steels. In order to assess the accuracy of our approach, first we perform a detailed study of the performance of the EMTO method for the Fe(16)C(1) binary system by comparing the EMTO results to those obtained using the projector augmented wave method. In the second step, we introduce different substitutional alloying elements (Al, Cr, Co, Ni) into the Fe matrix and study their impact on the structural parameters. We demonstrate that a small amount of Al, Co, and Ni enhances the tetragonal lattice ratio of Fe(16)C(1) whereas Cr leaves the ratio almost unchanged. The obtained trends are correlated with the single-crystal elastic parameters calculated for carbon-free alloys.
|
|
| 45. |
- Al-Zoubi, Noura, et al.
(författare)
-
The bain path of paramagnetic Fe-Cr based alloys
- 2011
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 110:1, s. 013708-
-
Tidskriftsartikel (refereegranskat)abstract
- Employing the first-principles exact muffin-tin orbital method in combination with the coherent potential approximation, we calculated the total energy and local magnetic moments of paramagnetic Fe-Cr-M (M = Cr, Mn, Fe, Co, Ni) alloys along the tetragonal distortion (Bain) path connecting the body centered cubic (bcc) and the face centered cubic (fcc) structures. The paramagnetic phase is modeled by the disordered local magnetic moment scheme. For all alloys, the local magnetic moments on Fe atoms decrease from the maximum value corresponding to the bcc phase toward the minimum value realized for the fcc phase. Cobalt atoms have non-vanishing local magnetic moments only for tetragonal lattices with c/a < 1.30, whereas the local magnetic moments of Mn show weak crystal structure dependence. We find that Cr stabilizes the bcc lattice and increases the energy barrier as going from the bcc toward the fcc phase. Both Co and Ni favor the fcc lattice and decrease the energy barrier relative to the bcc phase. On the other hand, the tetragonal distortion around the fcc phase is facilitated by Cr and to a somewhat lesser extent also by Ni, but strongly impeded by Co. Manganese has negligible effect on the structural energy difference as well as on the energy barrier along the Bain path. Our findings on the alloying induced softening or hardening of Fe-Cr based alloys against tetragonal distortions are important for understanding the interstitial driven martensitic transformations in alloy steels.
|
|
| 46. |
- Albrekt, Ann-Sofie, et al.
(författare)
-
Skin sensitizers differentially regulate signaling pathways in MUTZ-3 cells in relation to their individual potency
- 2014
-
Ingår i: Bmc Pharmacology & Toxicology. - : Springer Science and Business Media LLC. - 1471-2210 .- 2050-6511. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Due to the recent European legislations posing a ban of animal tests for safety assessment within the cosmetic industry, development of in vitro alternatives for assessment of skin sensitization is highly prioritized. To date, proposed in vitro assays are mainly based on single biomarkers, which so far have not been able to classify and stratify chemicals into subgroups, related to risk or potency. Methods: Recently, we presented the Genomic Allergen Rapid Detection (GARD) assay for assessment of chemical sensitizers. In this paper, we show how the genome wide readout of GARD can be expanded and used to identify differentially regulated pathways relating to individual chemical sensitizers. In this study, we investigated the mechanisms of action of a range of skin sensitizers through pathway identification, pathway classification and transcription factor analysis and related this to the reactive mechanisms and potency of the sensitizing agents. Results: By transcriptional profiling of chemically stimulated MUTZ-3 cells, 33 canonical pathways intimately involved in sensitization to chemical substances were identified. The results showed that metabolic processes, cell cycling and oxidative stress responses are the key events activated during skin sensitization, and that these functions are engaged differently depending on the reactivity mechanisms of the sensitizing agent. Furthermore, the results indicate that the chemical reactivity groups seem to gradually engage more pathways and more molecules in each pathway with increasing sensitizing potency of the chemical used for stimulation. Also, a switch in gene regulation from up to down regulation, with increasing potency, was seen both in genes involved in metabolic functions and cell cycling. These observed pathway patterns were clearly reflected in the regulatory elements identified to drive these processes, where 33 regulatory elements have been proposed for further analysis. Conclusions: This study demonstrates that functional analysis of biomarkers identified from our genomics study of human MUTZ-3 cells can be used to assess sensitizing potency of chemicals in vitro, by the identification of key cellular events, such as metabolic and cell cycling pathways.
|
|
| 47. |
- Alcala, Karine, et al.
(författare)
-
The relationship between blood pressure and risk of renal cell carcinoma
- 2022
-
Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 51:4, s. 1317-1327
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The relation between blood pressure and kidney cancer risk is well established but complex and different study designs have reported discrepant findings on the relative importance of diastolic blood pressure (DBP) and systolic blood pressure (SBP). In this study, we sought to describe the temporal relation between diastolic and SBP with renal cell carcinoma (RCC) risk in detail.METHODS: Our study involved two prospective cohorts: the European Prospective Investigation into Cancer and Nutrition study and UK Biobank, including >700 000 participants and 1692 incident RCC cases. Risk analyses were conducted using flexible parametric survival models for DBP and SBP both separately as well as with mutuality adjustment and then adjustment for extended risk factors. We also carried out univariable and multivariable Mendelian randomization (MR) analyses (DBP: ninstruments = 251, SBP: ninstruments = 213) to complement the analyses of measured DBP and SBP.RESULTS: In the univariable analysis, we observed clear positive associations with RCC risk for both diastolic and SBP when measured ≥5 years before diagnosis and suggestive evidence for a stronger risk association in the year leading up to diagnosis. In mutually adjusted analysis, the long-term risk association of DBP remained, with a hazard ratio (HR) per standard deviation increment 10 years before diagnosis (HR10y) of 1.20 (95% CI: 1.10-1.30), whereas the association of SBP was attenuated (HR10y: 1.00, 95% CI: 0.91-1.10). In the complementary multivariable MR analysis, we observed an odds ratio for a 1-SD increment (ORsd) of 1.34 (95% CI: 1.08-1.67) for genetically predicted DBP and 0.70 (95% CI: 0.56-0.88) for genetically predicted SBP.CONCLUSION: The results of this observational and MR study are consistent with an important role of DBP in RCC aetiology. The relation between SBP and RCC risk was less clear but does not appear to be independent of DBP.
|
|
| 48. |
|
|
| 49. |
- Ambrosch-Draxl, C., et al.
(författare)
-
First-principles study of oxygen ordering in YBa2Cu3O7-x
- 2000
-
Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 341, s. 1997-1998
-
Tidskriftsartikel (refereegranskat)abstract
- We have performed first-principles calculations considering different patterns of oxygen/vacancy ordering in the Cu-O chains of YBa2Cu3O7-x. From the total-energy values we determine the effective interactions of the oxygen atoms within the basal plane by using the cluster expansion technique. Furthermore, we discuss the effect of ordering to the density of states at the Fermi level.
|
|
| 50. |
- Amft, Martin, et al.
(författare)
-
Influence of the cluster dimensionality on the binding behavior of CO and O(2) on Au(13)
- 2012
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 136:2, s. 024312-
-
Tidskriftsartikel (refereegranskat)abstract
- We present an ab initio density functional theory study of the binding behavior of CO and O(2) molecules to two-and three-dimensional isomers of Au(13) in order to investigate the potential catalytic activity of this cluster towards low-temperature CO oxidation. First, we scanned the potential energy surface of Au(13) and studied the effect of spin-orbit coupling on the relative stabilities of the 21 isomers we identified. While spin-orbit coupling increases the stability of the three-dimensional more than the two-dimensional isomers, the ground state structure at 0 K remains planar. Second, we systematically studied the binding of CO and O(2) molecules onto the planar and three-dimensional structures lowest in energy. We find that the isomer dimensionality has little effect on the binding of CO to Au(13). O(2), on the other hand, binds significantly to the three-dimensional isomer only. The simultaneous binding of multiple CO molecules decreases the binding energy per molecule. Still, the CO binding remains stronger than the O(2) binding. We did not find a synergetic effect due to the co-adsorption of both molecular species. On the three-dimensional isomer, we find O(2) dissociation to be exothermic with an dissociation barrier of 1.44 eV.
|
|
