| 1. |
- Marouli, Eirini, et al.
(författare)
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Rare and low-frequency coding variants alter human adult height
- 2017
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 542:7640, s. 186-190
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Tidskriftsartikel (refereegranskat)abstract
- Height is a highly heritable, classic polygenic trait with approximately 700 common associated variants identified through genome-wide association studies so far. Here, we report 83 height-associated coding variants with lower minor-allele frequencies (in the range of 0.1-4.8%) and effects of up to 2 centimetres per allele (such as those in IHH, STC2, AR and CRISPLD2), greater than ten times the average effect of common variants. In functional follow-up studies, rare height increasing alleles of STC2 (giving an increase of 1-2 centimetres per allele) compromised proteolytic inhibition of PAPP-A and increased cleavage of IGFBP-4 in vitro, resulting in higher bioavailability of insulin-like growth factors. These 83 height-associated variants overlap genes that are mutated in monogenic growth disorders and highlight new biological candidates (such as ADAMTS3, IL11RA and NOX4) and pathways (such as proteoglycan and glycosaminoglycan synthesis) involved in growth. Our results demonstrate that sufficiently large sample sizes can uncover rare and low-frequency variants of moderate-to-large effect associated with polygenic human phenotypes, and that these variants implicate relevant genes and pathways.
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| 2. |
- Zheng, Weisen, et al.
(författare)
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Thermodynamic assessment of the Al-C-Fe system
- 2017
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Ingår i: Calphad. - : Elsevier. - 0364-5916 .- 1873-2984. ; 58, s. 34-49
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Tidskriftsartikel (refereegranskat)abstract
- The Al-C-Fe system was assessed in the framework of the CALPHAD approach. Through the critical review of thermochemical properties of liquid Al-Fe alloys, the binary Al-Fe description was revised to agree better with the experimental data. The partitioning model based on the Compound Energy Formalism (CEF) was utilized to describe the disordered and ordered bcc, fcc and κ phases. Moreover, ab initio calculations were performed to determine the enthalpies of formation of the ordered structures based on the bcc and fcc lattices in the binary Al-Fe and for the end-members of the κ phase in the ternary Al-C-Fe system. In order to simplify the database, the present work also employed a two-sublattice model to describe the B2 ordered phase in the Al-Fe system, which can be applied easily to diffusion simulations. Comprehensive comparison between the model-predicted and experimental data confirms that the present evaluation describe the Al-C-Fe system satisfactorily, especially the κ phase.
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| 3. |
- Chen, Xu, et al.
(författare)
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Ductility deterioration induced by L21 phase in ferritic alloy through Ti addition
- 2023
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Ingår i: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854. ; 25, s. 3273-3284
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Tidskriftsartikel (refereegranskat)abstract
- Ductility deterioration induced by L21-Ni2AlTi precipitates in the aged ferritic alloys was examined systematically by using a combination of scanning transmission electron microscope (STEM), mechanical tests and first-principles thermodynamic calculations. The experimental studies revealed that the strength and hardness of the aged Fe–10Cr–5Ni–1Al–1Ti ferritic alloy containing B2–NiAl and L21-Ni2AlTi precipitates were higher than that of the aged Fe–10Cr–5Ni–1Al ferritic alloy containing NiAl precipitates, whereas the elongation-to-failure decreased dramatically from 9.3% to 0.3% indicating an obvious ductility deterioration due to the formation of L21-Ni2AlTi precipitates. This was also confirmed by the observation of fracture transition mode from dimpled failure to cleavage failure. The first-principles calculations, concerning the precipitate/matrix interface, were carried out to provide a theoretical analysis for the ductile–brittle transition by means of empirical ductility criteria ratios G/B and (C12–C44)/B as well as cleavage energy. The cleavage energy results indicated an intrinsic brittleness of the L21-Ni2AlTi phase and the L21-Ni2AlTi/BCC-Fe interface. Our analysis revealed that the intrinsic brittleness of L21-Ni2AlTi phase and L21-Ni2AlTi/BCC-Fe interface plays a vital role in determining the deformation behavior of the aged Fe–10Cr–5Ni–1Al–1Ti alloy.
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| 4. |
- Cui, Luqing, et al.
(författare)
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New insights into the anisotropic ductility of additively manufactured Inconel 718
- 2023
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Ingår i: International journal of plasticity. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0749-6419 .- 1879-2154. ; 169
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Tidskriftsartikel (refereegranskat)abstract
- Anisotropic ductility in additively manufactured (AM) alloys, namely better ductility along the building direction (BD) has been extensively studied and traditionally attributed to the crystallographic texture. However, recent studies have shown significant ductility anisotropy in weakly or non-textured AM alloys, indicating that other factors may also play critical roles. To explore this, AM Inconel 718 with weak crystallographic texture was selected as the model material, and the in-situ high-energy X-ray diffraction tests together with multiscale microstructural characterization techniques were performed to explore the deformation micromechanisms. The results of this study, for the first time, revealed that the better ductility in the vertical specimen (loading parallel to BD) was partially due to the negative stress triaxiality factor (TF) of the {220} grains during plastic deformation, which results in the shrinkage or even healing of the microvoids. Furthermore, the & delta;-phase alignment in conjunction with grain boundary orientation were also proved to have a pronounced impact on the anisotropic ductility of AM alloys. On the other hand, though in the overall weak-textured microstructure, the proportion of 101 grains were marginally over other grains. Thus, the positive effect of {220} grains on ductility was stronger than the negative effect of {200} and {311} grains, contributing to the excellent failure elongation exceeding 12% for both samples. The findings of this study shed new light on the mechanisms underlying the anisotropic ductility of AM alloys and provide insight into strategies for enhancing their performance.
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| 5. |
- He, Shuang, et al.
(författare)
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Effective interactions and atomic ordering in Ni-rich Ni-Re alloys
- 2016
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Ingår i: Physical Review B Condensed Matter. - PRB : American Physical Society (APS). - 0163-1829 .- 1095-3795. ; 94:2
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Tidskriftsartikel (refereegranskat)abstract
- Interatomic interactions and ordering in fcc Ni-rich Ni-Re alloys are studied by means of first-principles methods combined with statistical mechanics simulations based on the Ising Hamiltonian. First-principles calculations are employed to obtain effective chemical and strain-induced interactions, as well as ordering energies and enthalpies of formation of random and ordered Ni-Re alloys. Based on the nonmagnetic enthalpies of formation, we speculate that the type of ordering can be different in alloys with Re content less than 10 at.%. We demonstrate that effective chemical interactions in this system are quite sensitive to the alloy composition, atomic volume, and magnetic state. In statistical thermodynamic simulations, we have used renormalized interactions, which correctly reproduce ordering energies obtained in the direct total energy calculations. Monte Carlo simulations for Ni 0.91 Re 0.09 alloy show that there exists a strong ordering tendency of the (112 0) type leading to precipitation of the D1 a ordered structure at about 940 K. Our results for the atomic short-range order indicate, however, that the presently applied theory overestimates the strength of the ordering tendency compared to that observed in the experiment.
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| 6. |
- He, Shuang, et al.
(författare)
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First-principles-based statistical thermodynamic study of atomic interactions and phase stability in Ni-rich Ni-W alloys
- 2023
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Ingår i: Calphad. - : Elsevier. - 0364-5916 .- 1873-2984. ; 82
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Tidskriftsartikel (refereegranskat)abstract
- Atomic interactions and phase stability in Ni-rich Ni-W alloys have been investigated by using first-principles methods and statistical thermodynamic simulations. First-principles methods have been employed to explore lattice expansion, enthalpies of formation, atomic interactions, and ordering energies of ordered as well as random structures in Ni-rich Ni-W alloys with consideration of the corresponding temperature-dependent magnetic states. It is found that atomic interactions in Ni-rich Ni-W alloys depend on alloy composition, atomic volume, and magnetic state. Nevertheless, the magnetic state of Ni greatly affects the formation enthalpies, which leads to a diverse phase separation behavior at finite temperature in Ni-rich Ni-W alloys. By using atomic interactions that reproduce the ordering energies obtained in the direct total energy calculations, our statistical thermodynamic simulations of chemical short-range order results show that fcc-based ordered D1a, D022, and Pt2Mo phases can be observed in Ni-20 at.% W, Ni-25 at.% W, and Ni-33 at.% W alloys, respectively. Moreover, the short-range order diffuse intensity and atomic stacking for aforementioned ordered phases have been analyzed, the order–disorder transition behaviors have been also investigated in detail for the Ni-rich Ni-W alloys up to 35 at.% W with comparison of current experimental results. Both magnetic state and alloy composition have the potential to induce the formation of distinct ordered phases, offering promising avenues for designing Ni-based alloys. The methodologies we used in this study can be applied to investigate the atomic interactions as well as phase stability in other alloy systems.
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| 7. |
- He, Shuang, et al.
(författare)
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First-principles study of Re-W interactions and their effects on the mechanical properties of γ/γ' interface in Ni-based single-crystal alloys
- 2023
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Ingår i: Materials Today Communications. - : Elsevier. - 2352-4928. ; 36
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of solutes and their interactions play a crucial role in determining the mechanical properties of the γ/γ′ interface in Ni-based single-crystal alloys. In this study, atomic interactions between Re and W and their alloying effects on the inter-phase cohesion of the γ/γ′ interface are investigated by first-principles calculations. Our results show that W atom exhibits a preference for partitioning into the γ phase, while the stability of the γ/γ′ interface can be enhanced due to the partitioning of W to the γ′ phase. Moreover, our results reveal that partitioned W atoms in the γ′ phase contribute to the strengthening of the γ/γ′ interface. Conversely, the dissolution of W atoms in the γ phase weakens the inter-phase cohesion. However, this detrimental effect can be mitigated by introducing of Re into the γ/γ′ interface. Partitioning of Re and W into separate phases yields minimal alterations in interaction energies, resulting in a notable enhancement of inter-phase cohesion when compared to the partitioning of Re and W within γ phase of the γ/γ′ interface. Additionally, the partitioning of solute atoms at the γ/γ′ interface leads to local lattice distortion and interfacial energy reduction, which contribute to the enhancement of inter-phase cohesion of the γ/γ′ interface. As a result, a model is proposed for interpretation of crack propagation at the γ/γ′ interface at the threshold region with the presence of tensile stress in Ni-based single-crystal alloys.
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| 8. |
- He, Shuang, et al.
(författare)
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Interactions and phase stability in Ni-rich Ni-W alloys
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Interatomic interactions and phase transformation in Ni-rich Ni-W alloys are investigated using rst-principlesmethods and statistical thermodynamics simulations. The formation enthalpies of fcc and bcc random as wellas some fcc-based ordered structures are determined in the ferromagnetic and nonmagnetic states. The effective interactions are calculated in supercell ab initio calculations and using screened generalized perturbation method(SGPM). We find the stable fcc-based ordered structures are D1a, DO22 and Pt2Mo phases and they can be observed in the Ni-25 at.% W, Ni-25 at.% W and Ni-33 at.% W alloys, respectively. The calculated atomic short-range order results are in reasonable agreement with experiments and other theoretical investigations.
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| 9. |
- He, Shuang, 1986-
(författare)
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Interactions and phase stability in Ni-rich binary alloys
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ni-based superalloys are the important materials for gas turbines in advancedaeroplane engines . The addition of refractory elements to these superalloys,such as rhenium and tungsten, can significantly improve the hightemperatureperformance by so-called solid-solution hardening. Although thestrengthening effect of refractory elements in Ni-based superalloys have beenknown for a long time, the effective interactions among alloying componentsas well as the atomic ordering in the alloy systems are still under investigationand even under debate. In this work, we study these interactions and thisordering for two binary alloys, Ni-rich Ni-Re and Ni-rich Ni-W, by means ofab initio simulations and statistical mechanics simulations based on the IsingHamiltonian.For the Ni-rich Ni-Re alloys, we show that the effective cluster interactionsvary substantially depending on the temperature, concentration of the componentsand the magnetic state of the matrix. The strain-induced interactionshave large contribution to the nearest-neighbor pair-interactions and some multisitecluster-interactions in the ferromagnetic and nonmagnetic states. Theordering tendency of binary Ni-Re alloy systems can be predicted in terms ofordering energy and enthalpy of formation. We show that the D1a orderedstructure should be stable at the concentration of 20 at.% Re in the Ni-rich Ni–Re alloy system. The Monte Carlo simulations of Ni-Re random alloysshow the existence with the D1a-Ni4Re ordered structure at low temperatures.We also calculated lattice parameters for different compositions of Ni-rich Ni-W alloys, and we find that lattice parameters of random Ni-W alloys increaselinearly with the concentration of W. This is in good agreement withthe Vegard’s law predictions and experimental data. We investigated phasestability of Ni-rich Ni-W alloys in terms of the enthalpies of formation andordering energies. We find the chemical pair interactions are sensitive to themagnetic state and concentration. The calculated strain-induced interactionsare quite large for the first coordination shell, which is due to a large sizemismatch of Ni and W. Taking local lattice relaxation into account, the Ni-Wsystems were modeled by Monte Carlo method. The D1a-Ni4W ordered structurecan be observed up to 22 at.% W. In higher concentrations of W, in ourMC calculations, the DO22-Ni3W and Pt2Mo-Ni2W ordered structures can beobserved in Ni-25 at.% W alloy and Ni-33 at.% W alloy, respectively.
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| 10. |
- He, Shuang, et al.
(författare)
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Solubility and segregation of B in paramagnetic fcc Fe
- 2022
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Ingår i: Physical Review Materials. - : American Physical Society (APS). - 2475-9953. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Boron solubility and segregation in paramagnetic (PM) fcc iron have been investigated by means of DFT calculations. The results focus on the Boron site preference in both bulk and coincidence site lattice model Sigma 5 (012) GB in fcc Fe and evaluate the validity of different model approaches for modeling the PM state. Boron and PM fcc iron are predicted to form an interstitial solid solution. The PM state model and pressure correction have been introduced into the 0 K DFT calculations to evaluate Boron solubility in fcc Fe as a function of its thermal lattice expansion within the temperature range of 0-1670 K. The relatively high segregation energy of Boron of about -1.57 eV to both interstitial and substitutional GB sites at 0 K is predicted to substantially decrease with thermal lattice expansion, reaching the value of about -0.3 eV at the lattice parameter of fcc Fe corresponding to 1670 K. The contribution of the PM state to the segregation energy was found to be of the order of 0.1 eV compared to the nonmagnetic calculations.
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