| 1. |
- Emerging Risk Factors, Collaboration, et al.
(författare)
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The Emerging Risk Factors Collaboration: analysis of individual data on lipid, inflammatory and other markers in over 1.1 million participants in 104 prospective studies of cardiovascular diseases
- 2007
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Ingår i: Eur J Epidemiol. - 0393-2990. ; 22:12, s. 839-69
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Tidskriftsartikel (refereegranskat)abstract
- Many long-term prospective studies have reported on associations of cardiovascular diseases with circulating lipid markers and/or inflammatory markers. Studies have not, however, generally been designed to provide reliable estimates under different circumstances and to correct for within-person variability. The Emerging Risk Factors Collaboration has established a central database on over 1.1 million participants from 104 prospective population-based studies, in which subsets have information on lipid and inflammatory markers, other characteristics, as well as major cardiovascular morbidity and cause-specific mortality. Information on repeat measurements on relevant characteristics has been collected in approximately 340,000 participants to enable estimation of and correction for within-person variability. Re-analysis of individual data will yield up to approximately 69,000 incident fatal or nonfatal first ever major cardiovascular outcomes recorded during about 11.7 million person years at risk. The primary analyses will involve age-specific regression models in people without known baseline cardiovascular disease in relation to fatal or nonfatal first ever coronary heart disease outcomes. This initiative will characterize more precisely and in greater detail than has previously been possible the shape and strength of the age- and sex-specific associations of several lipid and inflammatory markers with incident coronary heart disease outcomes (and, secondarily, with other incident cardiovascular outcomes) under a wide range of circumstances. It will, therefore, help to determine to what extent such associations are independent from possible confounding factors and to what extent such markers (separately and in combination) provide incremental predictive value.
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| 2. |
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| 3. |
- Pietersz, R. N. I., et al.
(författare)
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Prophylactic platelet transfusions
- 2012
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Ingår i: Vox Sanguinis. - : Wiley. - 0042-9007 .- 1423-0410. ; 103:2, s. 159-176
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Ruess, H., et al.
(författare)
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HPPMS deposition from composite targets : Effect of two orders of magnitude target power density changes on the composition of sputtered Cr-Al-C thin films
- 2017
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Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 145, s. 285-289
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Tidskriftsartikel (refereegranskat)abstract
- The effect of target power density, substrate bias potential and substrate temperature on the thin film composition was studied. A Cr-Al-C composite target was sputtered utilizing direct current (DCMS: 2.3 W/cm(2)) and high power pulsed magnetron sputtering (HPPMS: 373 W/cm(2)) generators. At floating potential, all Cr-Al-C thin films showed similar compositions, independently of the applied target power density. However, as substrate bias potential was increased to -400 V, aluminum deficiencies by a factor of up to 1.6 for DCMS and 4.1 for HPPMS were obtained. Based on the measured ion currents at the substrate, preferential re-sputtering of Al is suggested to cause the dramatic Al depletion. As the substrate temperature was increased to 560 degrees C, the Al concentration was reduced by a factor of up to 1.9 compared to the room temperature deposition. This additional reduction may be rationalized by thermally induced desorption being active in addition to re-sputtering.
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| 5. |
- Aghda, Soheil Karimi, et al.
(författare)
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Ion kinetic energy- and ion flux-dependent mechanical properties and thermal stability of (Ti,Al)N thin films
- 2023
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Ingår i: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 250
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Tidskriftsartikel (refereegranskat)abstract
- Ion-irradiation-induced changes in structure, elastic properties, and thermal stability of metastable c-(Ti,Al)N thin films synthesized by high-power pulsed magnetron sputtering (HPPMS) and cathodic arc deposition (CAD) are systematically investigated by experiments and density functional theory (DFT) simulations. While films deposited by HPPMS show a random orientation at ion kinetic energies (Ek)>105 eV, an evolution towards (111) orientation is observed in CAD films for Ek>144 eV. The measured ion energy flux at the growing film surface is 3.3 times larger for CAD compared to HPPMS. Hence, it is inferred that formation of the strong (111) texture in CAD films is caused by the ion flux-and ion energy-induced strain energy minimization in defective c-(Ti,Al)N. The ion energy-dependent elastic modulus can be rationalized by considering the ion energy-and orientation -dependent formation of point defects from DFT predictions: The balancing effects of bombardment-induced Frenkel defects formation and the concurrent evolution of compressive intrinsic stress result in the apparent independence of the elastic modulus from Ek for HPPMS films without preferential orientation. However, an ion energy-dependent elastic modulus reduction of similar to 18% for the CAD films can be understood by considering the 34% higher Frenkel pair concentration formed at Ek=182 eV upon irradiation of the experimentally observed (111)-oriented (Ti,Al)N in comparison to the (200)-configuration at similar Ek. Moreover, the effect of Frenkel pair concentration on the thermal stability of metastable c-(Ti,Al)N is investigated by differential scanning calorimetry: Ion-irradiation-induced increase in Frenkel pairs concentration retards the wurtzite formation temperature by up to 206 degrees C.
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| 6. |
- Greczynski, Grzegorz, et al.
(författare)
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Extended metastable Al solubility in cubic VAlN by metal-ion bombardment during pulsed magnetron sputtering: film stress vs subplantation
- 2017
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Ingår i: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 122:2
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic ion-recoil mixing of near-film-surface atomic layers is commonly used to increase the metastable solubility limit x(max) in otherwise immiscible thin film systems during physical vapor deposition. Recently, Al subplantation achieved by irradiating the film growth surface with Al+ metal-ion flux was shown to result in an unprecedented x(max) for VAlN, far above values obtained with gas ion irradiation. However, it is reasonable to assume that ion irradiation necessary for subplantation also leads to a compressive stress sigma buildup. In order to separate the effects of Al+ bombardment on sigma and x(max), and realize low-stress high-x(max) nitride alloys, we grow metastable cubic V1-xAlxN (0.17 amp;lt;= x amp;lt;= 0.74) films using reactive magnetron sputtering under different ion irradiation conditions. Al and V targets are operated in Ar/N-2 discharges employing (i) conventional DC (Ar+, N-2(+)), (ii) hybrid High-power pulsed magnetron sputtering (HIPIMS)/DC processing with one type of metal ion present (Al+ or V+/V2+), and (iii) HIPIMS with concurrent Al+ and V+/V2+ fluxes. Comparison to the ab initio calculated Al solubility limit reveals that x(max) = 0.55 achieved with V+/V2+ irradiation is entirely accountable for by stress. In contrast, Al+ fluxes provide a substantial increase in x(max) to 0.63, which is 12% higher than that expected based on the stress-induced increase in metastable solubility. Correlative stress and atom probe tomography data confirm that the metastable Al solubility enhancement is enabled by Al+ subplantation. The here proposed processing strategy allows for growth of single-phase cubic nitride alloys with significantly increased Al concentrations embodying tremendous promise for substantial improvements in high temperature oxidation resistance and mitigates the risk of stress-induced adhesive or cohesive coating failure. Published by AIP Publishing.
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| 7. |
- Greczynski, Grzegorz, et al.
(författare)
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Unprecedented Al supersaturation in single-phase rock salt structure VAlN films by Al+ subplantation
- 2017
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Ingår i: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 121:17
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Tidskriftsartikel (refereegranskat)abstract
- Modern applications of refractory ceramic thin films, predominantly as wear-protective coatings on cutting tools and on components utilized in automotive engines, require a combination of excellent mechanical properties, thermal stability, and oxidation resistance. Conventional design approaches for transition metal nitride coatings with improved thermal and chemical stability are based on alloying with Al. It is well known that the solubility of Al in NaCl-structure transition metal nitrides is limited. Hence, the great challenge is to increase the Al concentration substantially while avoiding precipitation of the thermodynamically favored wurtzite-AlN phase, which is detrimental to mechanical properties. Here, we use VAlN as a model system to illustrate a new concept for the synthesis of metastable single-phase NaCl-structure thin films with the Al content far beyond solubility limits obtained with conventional plasma processes. This supersaturation is achieved by separating the film-forming species in time and energy domains through synchronization of the 70-mu s-long pulsed substrate bias with intense periodic fluxes of energetic Al+ metal ions during reactive hybrid high power impulse magnetron sputtering of the Al target and direct current magnetron sputtering of the V target in the Ar/N-2 gas mixture. Hereby, Al is subplanted into the cubic VN grains formed by the continuous flux of low-energy V neutrals. We show that Al subplantation enables an unprecedented 42% increase in metastable Al solubility limit in V1-xAlxN, from x-0.52 obtained with the conventional method to 0.75. The elastic modulus is 325 +/- 5GPa, in excellent agreement with density functional theory calculations, and approximately 50% higher than for corresponding films grown by dc magnetron sputtering. The extension of the presented strategy to other Al-ion-assisted vapor deposition methods or materials systems is straightforward, which opens up the way for producing supersaturated single-phase functional ceramic alloy thin films combining excellent mechanical properties with high oxidation resistance. Published by AIP Publishing.
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| 8. |
- Holzapfel, Damian M., et al.
(författare)
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Influence of ion irradiation-induced defects on phase formation and thermal stability of Ti0.27Al0.21N0.52 coatings
- 2022
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Ingår i: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 237
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Tidskriftsartikel (refereegranskat)abstract
- The influence of changes induced by ion irradiation on structure and thermal stability of metastable cubic (Ti,Al)N coatings deposited by cathodic arc evaporation is systematically investigated by correlating experiments and theory. Decreasing the nitrogen deposition pressure from 5.0 to 0.5 Pa results in an ion flux-enhancement by a factor of three and an increase of the average ion energy from 15 to 30 eV, causing the stress-free lattice parameter to expand from 4.170 to 4.206 Å, while the chemical composition of Ti0.27Al0.21N0.52 remains unchanged. The 0.9% lattice parameter increase is a consequence of formation of Frenkel pairs induced by ion bombardment, as revealed by density functional theory (DFT) simulations. The influence of the presence of Frenkel pairs on the thermal stability of metastable Ti0.27Al0.21N0.52 is investigated by scanning transmission electron microscopy, differential scanning calorimetry, atom probe tomography and in-situ synchrotron X-ray powder diffraction. It is demonstrated that the ion flux and ion energy induced formation of Frenkel pairs increases the thermal stability as the Al diffusion enabled crystallization of the wurtzite solid solution is retarded. This can be rationalized by DFT predictions since the presence of Frenkel pairs increases the activation energy for Al diffusion by up to 142%. Hence, the thermal stability enhancement is caused by a hitherto unreported mechanism - the Frenkel pair impeded Al mobility and thereby retarded formation of wurtzite solid solution.
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| 9. |
- Kashani, Amir Hossein Navidi, et al.
(författare)
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Morphology, mechanical properties, and oxidation behavior of stoichiometric Ti0.33-xAlxB0.67 coatings (x=0.04, 0.15, 0.21, and 0.28)
- 2024
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Ingår i: Acta Materialia. - : Elsevier. - 1359-6454 .- 1873-2453. ; 270
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Tidskriftsartikel (refereegranskat)abstract
- Stoichiometric Ti0.33-xAlxB0.67 coatings with x = 0.04, 0.15, 0.21, and 0.28 were synthesized by magnetron sputtering and characterized regarding phase formation, mechanical properties, and oxidation behavior. By increasing the Al concentration from 4 to 28 at.%, the measured elastic modulus (496±19 GPa) and unit cell volume (25.646 Å3 ) decreased by 33 and 0.8 %, respectively. The Al concentration induced changes in measured elastic modulus and unit cell volume are in very good agreement with ab initio predictions, as the maximum deviations between experiment and theory, observed here, are 12 and 1.1 %, respectively. The corresponding hardness values decreased by 45 % from 22±1 to 12±1 GPa. The oxidation experiments were performed in ambient air at 700, 800, and 900 °C for 1, 4, and 8 h. Analysis by scanning transmission electron microscopy (STEM) revealed a bimodal, strongly Al concentration-dependent oxidation behavior where films containing ≤15 at.% of Al form a porous, non-passivating crystalline oxide scale containing Ti -rich as well as Al -rich oxide regions, while the formation of a passivating, dense, X-ray amorphous oxide scale was observed for films containing ≥ 21 at.% of Al. Coincident with the passive scale formation for Al concentrations ≥ 21 at.%, the elastic modulus decreases by ≥ 32.6 % compared to TiB2 and can be rationalized based on Al concentration induced bond weakening as revealed by the concomitant cohesive energy reduction of ≥ 22 %.
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| 10. |
- Kashani, Amir Hossein Navidi, et al.
(författare)
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Synthesis and oxidation behavior of Ti0.35Al0.65By (y=1.7-2.4) coatings
- 2022
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 442
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Tidskriftsartikel (refereegranskat)abstract
- The effect of B concentration on phase formation and oxidation resistance of (Ti0.35Al0.65)By coatings with y = 1.7, 2.0, 2.4 was investigated. Elemental B targets in radio frequency mode and a compound Ti0.4Al0.6 target in direct current mode were sputtered. The B concentration was varied systematically by adjusting the applied power to the respective magnetrons, while keeping the power supplied to the magnetron with the Ti0.4Al0.6 target constant. Measured lattice parameters and elastic properties are consistent with ab initio predictions. The oxidation resistance at 700 degrees C in air for up to 8 h was compared to a cathodic arc evaporated (Ti0.37Al0.63)0.49N0.51 coating with an Al/Ti ratio of 1.69 +/- 0.20 which is very similar to 1.84 +/- 0.40 for the boride coatings. Scanning transmission electron microscopy imaging revealed oxide scale thicknesses of 39 +/- 7 and 101 +/- 25 nm for (Ti0.35Al0.65)B2.0 and (Ti0.37Al0.63)0.49N0.51 after 8 h, respectively. Hence, the close to stoichiometric diboride outperforms the nitride coating. This behavior can be understood based on composition and structure analysis of the oxide scales: While the protective layer on the diboride is primarily composed of Al and O, the porous oxide layer on the nitride coating contains Ti, Al and O.
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