| 1. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - 2050-084X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.522.7) and 16.5 cm (13.319.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 2. |
- Bentham, James, et al.
(författare)
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A century of trends in adult human height
- 2016
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3– 19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8– 144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 3. |
- Conti, David, V, et al.
(författare)
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Trans-ancestry genome-wide association meta-analysis of prostate cancer identifies new susceptibility loci and informs genetic risk prediction
- 2021
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Ingår i: Nature Genetics. - : Springer Nature. - 1061-4036 .- 1546-1718. ; 53:1, s. 65-75
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Tidskriftsartikel (refereegranskat)abstract
- Prostate cancer is a highly heritable disease with large disparities in incidence rates across ancestry populations. We conducted a multiancestry meta-analysis of prostate cancer genome-wide association studies (107,247 cases and 127,006 controls) and identified 86 new genetic risk variants independently associated with prostate cancer risk, bringing the total to 269 known risk variants. The top genetic risk score (GRS) decile was associated with odds ratios that ranged from 5.06 (95% confidence interval (CI), 4.84-5.29) for men of European ancestry to 3.74 (95% CI, 3.36-4.17) for men of African ancestry. Men of African ancestry were estimated to have a mean GRS that was 2.18-times higher (95% CI, 2.14-2.22), and men of East Asian ancestry 0.73-times lower (95% CI, 0.71-0.76), than men of European ancestry. These findings support the role of germline variation contributing to population differences in prostate cancer risk, with the GRS offering an approach for personalized risk prediction. A meta-analysis of genome-wide association studies across different populations highlights new risk loci and provides a genetic risk score that can stratify prostate cancer risk across ancestries.
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| 4. |
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| 5. |
- Herrmann, Mathias, et al.
(författare)
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Silicon nitride nanoceramics densified by dynamic grain sliding
- 2010
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Ingår i: Journal of Materials Research. - : Springer Science and Business Media LLC. - 0884-2914 .- 2044-5326. ; 25, s. 2354-2361
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Tidskriftsartikel (refereegranskat)abstract
- The densification behaviors of two silicon nitride nanopowder mixtures based respectively on a-Si3N4 and ß-Si3N4 as the major phase constituent were studied by spark plasma sintering. Sintering conditions were established where a low viscous liquid not in equilibrium with the main crystalline constituent(s) stimulated the grain sliding yet did not activate the reprecipitation mechanism that unavoidably yields grain growth. By this way of dynamic grain sliding full densification of silicon nitride nanoceramics was achieved with no noticeable involvement of a- to ß-Si3N4 phase transformation and grain growth. This processing principle opens the way toward flexible and precise tailoring of the microstructures and properties of Si3N4 ceramics. The obtained silicon nitride nanoceramics showed improved wear resistance, particularly under higher Hertzian stresses.
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| 6. |
- Hu, Jianfeng, et al.
(författare)
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A general mechanism of grain growth -I. Theory
- 2021
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Ingår i: Journal of Materiomics. - : Elsevier BV. - 2352-8478 .- 2352-8486. ; 7:5, s. 1007-1013
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Tidskriftsartikel (refereegranskat)abstract
- The behaviors of grain growth dominate the formation of the microstructure inside polycrystalline materials and thus strongly influence their practical performances. However, grain growth behaviors still remain ambiguous and thus lack a mathematical formula to describe the general evolution despite decades of efforts. Here, we propose a new migration model of grain boundary (GB) and further derive a mathematical expression to depict the general evolution of grain growth in the cellular structures. The expression incorporates the variables influencing growth rate (e.g. GB features, grain size and local grain size distribution) and thus reveals how the normal, abnormal and stagnant behaviors of grain growth occur in polycrystalline systems. In addition, our model correlates quantitatively GB roughening transition with grain growth behavior. The general growth theory may provide new insights into the GB thermodynamics and kinetics during the cellular structure evolution.
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| 7. |
- Hu, Jianfeng, et al.
(författare)
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Grain growth by multiple ordered coalescence of nanocrystals during spark plasma sintering of SrTiO3 nanopowders
- 2012
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 60:18, s. 6405-6412
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Tidskriftsartikel (refereegranskat)abstract
- Sintering is the most widely applied densification process for manufacturing polycrystalline materials in powder metallurgy and ceramic industries. Grain growth behavior during sintering has a crucial influence on the final microstructure and thus the achieved performance. So far, it has been accepted that grain growth, based on classic crystal growth theory, takes place via atomic diffusion driven by excess interfacial energy. This paper presents a novel grain growth mechanism resulting from multiple ordered coalescence of nanocrystals via the activation of rapid grain motions. In rapid solid-state sintering of a strontium titanate (SrTiO3) nanopowder, individual SrTiO3 nanocrystals can act as the building blocks and self-assemble to form larger grains. A quasi-liquid interfacial film achieved by surface melting of the nanocrystals plays an essential role in this new process by facilitating the grain motion and ordered coalescence of nanocrystals. The imperfect ordered coalescence of nanocrystals introduce deep structural heterogeneities characterized by the unique quasi-interfaces inside grown grains of single crystal signature. The quasi-interfaces consist of the vacancy arrays and/or aggregated line defects.
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| 8. |
- Hu, Jianfeng, 1979-
(författare)
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Grain growth by Ordered Coalescence of crystallites in Ceramics : Grain Growth Mechanisms, Microstructure Evolution and Sintering
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Grain growth and densification process play the two most crucial roles on the microstructure evolution and the achieved performances during sintering of ceramics. In this thesis, the grain growth of SrTiO3, BaTiO3-SrTiO3 solid solutions and Si3N4 ceramics during spark plasma sintering (SPS) were investigated by electron microscopy.SrTiO3 ceramics starting from nanopowders were fabricated by SPS. A novel grain growth mechanism was discovered and named as ordered coalescence (OC) of nanocrystals. This mechanism involved nanocrystals as building blocks and is distinguished from atomic layer epitaxial growth (AEG) in classical sintering theory. The results also revealed that the dominant grain growth mechanism can be changed by varying heating rates. Low rate (10°C/min) gives AEG, whereas high rates (≥ 50°C/min) yields three-dimensional coalescence of nanocrystals, i.e. OC.BaTiO3-SrTiO3 sintered bodies were made by SPS of BaTiO3 and SrTiO3 nanopowders mixtures. A novel Sr1-xBaxTiO3 “solid solution” with mosaic-like single crystal structure was manufactured by OC of the precursor crystallites. This reveals a new path for preparation of solid solution grains or composites. Si3N4 ceramics were prepared from α- or β-Si3N4 nanopowders at the same SPS conditions. The anisotropic OC of precipitated β-Si3N4 crystallites gives elongated β-Si3N4 grains at 1650°C using α-Si3N4 nanopowder. In contrast, AEG leads to the equi-axed β-Si3N4 grains using β-Si3N4 nanopowder. The metastable α- to β-Si3N4 phase transformation and OC accelerates anisotropic grain growth.Grain motions contribute to the densification process during pressureless sintered 3Y-ZrO2 (>87%TD) or SPS of SrTiO3 (>92%TD) ceramics. This extends the sintering range for active grain re-arrangement over that predicted by classical theory.In this thesis a new grain growth mechanism (OC) is proved by using SPS and nanopowders. By OC the microstructural evolution can be manipulated.
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| 9. |
- Hu, Jianfeng, et al.
(författare)
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Grain growth competition during sintering of SrTiO3 nanocrystals : Ordered coalescence of nanocrystals versus conventional mechanism
- 2021
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 194
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Tidskriftsartikel (refereegranskat)abstract
- Grain growth plays a crucial role in developing the microstructures of polycrystalline materials during heating treatment. In this work, SrTiO3 ceramics sintered at different heating rates (10 degrees C/min and 100 degrees C/min) display the distinctly different grain growth behaviors and microstructures between them. The onset temperature of rapid grain growth and mechanical-performance-related fracture mode are apparently different between these two sets of samples. Two grain growth mechanisms are demonstrated to dominate separately the sintering of SrTiO3 nanocrystals at different heating rates, i.e. conventional mechanism of atom-by-atom additions for grain growth at 10 degrees C/min and ordered coalescence of nanocrystals for grain growth at 100 degrees C/min. It is demonstrated that the switch of growth mechanisms is determined by the competition between the activation of grain motions and the formation of steady neck among grains.
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| 10. |
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