| 1. |
- Sampson, Joshua N., et al.
(författare)
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Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for 13 Cancer Types
- 2015
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 0027-8874 .- 1460-2105. ; 107:12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, h(l)(2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (rho = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (rho = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (rho = 0.51, SE = 0.18), and bladder and lung (rho = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.
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| 2. |
- Wang, Zhaoming, et al.
(författare)
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Imputation and subset-based association analysis across different cancer types identifies multiple independent risk loci in the TERT-CLPTM1L region on chromosome 5p15.33
- 2014
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:24, s. 6616-6633
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies (GWAS) have mapped risk alleles for at least 10 distinct cancers to a small region of 63 000 bp on chromosome 5p15.33. This region harbors the TERT and CLPTM1L genes; the former encodes the catalytic subunit of telomerase reverse transcriptase and the latter may play a role in apoptosis. To investigate further the genetic architecture of common susceptibility alleles in this region, we conducted an agnostic subset-based meta-analysis (association analysis based on subsets) across six distinct cancers in 34 248 cases and 45 036 controls. Based on sequential conditional analysis, we identified as many as six independent risk loci marked by common single-nucleotide polymorphisms: five in the TERT gene (Region 1: rs7726159, P = 2.10 × 10(-39); Region 3: rs2853677, P = 3.30 × 10(-36) and PConditional = 2.36 × 10(-8); Region 4: rs2736098, P = 3.87 × 10(-12) and PConditional = 5.19 × 10(-6), Region 5: rs13172201, P = 0.041 and PConditional = 2.04 × 10(-6); and Region 6: rs10069690, P = 7.49 × 10(-15) and PConditional = 5.35 × 10(-7)) and one in the neighboring CLPTM1L gene (Region 2: rs451360; P = 1.90 × 10(-18) and PConditional = 7.06 × 10(-16)). Between three and five cancers mapped to each independent locus with both risk-enhancing and protective effects. Allele-specific effects on DNA methylation were seen for a subset of risk loci, indicating that methylation and subsequent effects on gene expression may contribute to the biology of risk variants on 5p15.33. Our results provide strong support for extensive pleiotropy across this region of 5p15.33, to an extent not previously observed in other cancer susceptibility loci.
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| 3. |
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| 4. |
- Dong, Zhihua, et al.
(författare)
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Computation of Phase Fractions in Austenite Transformation with the Dilation Curve for Various Cooling Regimens in Continuous Casting
- 2016
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer. - 1073-5615 .- 1543-1916. ; 47:3, s. 1553-1564
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Tidskriftsartikel (refereegranskat)abstract
- A concise model is applied to compute the microstructure evolution of austenite transformation by using the dilation curve of continuously cast steels. The model is verified by thermodynamic calculations and microstructure examinations. When applying the model, the phase fractions and the corresponding transforming rates during austenite transformation are investigated at various cooling rates and chemical compositions. In addition, ab initio calculations are performed for paramagnetic body-centered-cubic Fe to understand the thermal expansion behavior of steels at an atomic scale. Results indicate that by increasing the cooling rate, the final volume fraction of ferrite/pearlite will gradually increase/decrease with a greater transforming rate of ferrite. The ferrite fraction increases after austenite transformation with lowering of the carbon content and increasing of the substitutional alloying fractions. In the austenite transformation, the thermal expansion coefficient is sequentially determined by the forming rate of ferrite and pearlite. According to the ab initio theoretical calculations for the single phase of ferrite, thermal expansion emerges from magnetic evolution and lattice vibration, the latter playing the dominant role. The theoretical predictions for volume and thermal expansion coefficient are in good agreement with the experimental data.
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| 5. |
- Wang, Gang, et al.
(författare)
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Aggregation control in natural brush-printed conjugated polymer films and implications for enhancing charge transport
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 114:47, s. E10066-E10073
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Tidskriftsartikel (refereegranskat)abstract
- Shear-printing is a promising processing technique in organic electronics for microstructure/charge transport modification and large-area film fabrication. Nevertheless, the mechanism by which shear-printing can enhance charge transport is not well-understood. In this study, a printing method using natural brushes is adopted as an informative tool to realize direct aggregation control of conjugated polymers and to investigate the interplay between printing parameters, macromolecule backbone alignment and aggregation, and charge transport anisotropy in a conjugated polymer series differing in architecture and electronic structure. This series includes (i) semicrystalline hole-transporting P3HT, (ii) semicrystalline electron transporting N2200, (iii) low-crystallinity hole-transporting PBDTT-FTTE, and (iv) low-crystallinity conducting PEDOT:PSS. The (semi-)conducting films are characterized by a battery of morphology and microstructure analysis techniques and by charge transport measurements. We report that remarkably enhanced mobilities/conductivities, as high as 5.7x/3.9x, are achieved by controlled growth of nanofibril aggregates and by backbone alignment, with the adjusted R-2 (R-adj(2)) correlation between aggregation and charge transport as high as 95%. However, while shear-induced aggregation is important for enhancing charge transport, backbone alignment alone does not guarantee charge transport anisotropy. The correlations between efficient charge transport and aggregation are clearly shown, while mobility and degree of orientation are not always well-correlated. These observations provide insights into macroscopic charge transport mechanisms in conjugated polymers and suggest guidelines for optimization.
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| 6. |
- Wang, Suhao, et al.
(författare)
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Effect of Backbone Regiochemistry on Conductivity, Charge Density, and Polaron Structure of n-Doped Donor-Acceptor Polymers
- 2019
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 31:9, s. 3395-3406
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the influence of backbone regiochemistry on the conductivity, charge density, and polaron structure in the widely studied n-doped donor-acceptor polymer poly[N,N-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5-(2,2-bithiophene) [P-(NDI2OD-T2)]. In contrast to classic semicrystalline polymers such as poly(3-hexylthiophene) (P3HT), the regioirregular (RI) structure of the naphthalenediimide (NDI)-bithiophene (T2) backbone does not alter the intramolecular steric demand of the chain versus the regioregular (RR) polymer, yielding RI-P(NDI2OD-T2) with similar energetics and optical features as its RR counterpart. By combining the electrical, UV-vis/infrared, X-ray diffraction, and electron paramagnetic resonance data and density functional theory calculations, we quantitatively characterized the conductivity, aggregation, crystallinity, and charge density, and simulated the polaron structures, molecular vibrations, and spin density distribution of RR-/RI-P(NDI2OD-T2). Importantly, we observed that RI-P(NDI2OD-T2) can be doped to a greater extent compared to its RR counterpart. This finding is remarkable and contrasts benchmark P3HT, allowing us to uniquely study the role of regiochemistry on the charge-transport properties of n-doped donor-acceptor polymers.
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| 7. |
- Ai, Songyuan, et al.
(författare)
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Ab Initio Calculations on Elastic Properties of IF Steel Matrix Phase at High Temperature Based on Lattice Expansion Theory
- 2020
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 10:2
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Tidskriftsartikel (refereegranskat)abstract
- Elucidating the evolution law of the elastic properties of the matrix phase is of great significance for the control of steel properties and quality during continuous casting and subsequent heat treatment. In this paper, thermal expansion experiments and ab initio calculations are used to study the elastic properties of the interstitial free (IF) steel matrix phase in different magnetic states and crystal structures. The results show that the bulk modulus B and the tetragonal shear elastic constant C' for the entire temperature range decrease with increasing temperature, but C-44 is the opposite. While from paramagnetic (PM) to ferromagnetic (FM) state, C'(C-44) have changed similar to 188% (similar to 27%), B increases by similar to 55% during the crystal structure change (fcc -> bcc). With the FM to PM state, the Zener anisotropy parameter increases sharply, and Young's modulus decreases significantly in the [001] direction; the maximum difference is similar to 76 GPa. The evolution rate of average Young's modulus in single bcc-phase FM (fcc-phase PM) range reaches similar to 5.5(similar to 5.6) x 10(-2) GPa K-1. The research provides an effective method for ab initio calculation of the elastic properties of interstitial free and ultra-low carbon steels at high temperature, also furnishing a basis for the application of ab initio calculations to the high temperature performance of steel materials.
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| 8. |
- Ai, S., et al.
(författare)
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Ab Initio Study on Continuous Evolution of Mechanical Properties in Phase-Transition Region of Low-Carbon Steel
- 2020
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Ingår i: Steel Research International. - : Wiley-VCH Verlag. - 1611-3683 .- 1869-344X.
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Tidskriftsartikel (refereegranskat)abstract
- To control steel quality during continuous casting and subsequent heat treatment, an understanding of the evolution laws of mechanical properties during the austenite transition and the underlying mechanisms is of importance. Herein, the peak separation method is used to investigate the expansion behaviors in low-carbon steel. And the elastic properties of the matrix phase are calculated using the exact muffin-tin orbitals (EMTO) method. A continuous evolution model of high-temperature properties in the phase-transition region is established for ab initio data and experimental results. The evolution laws of the tetragonal shear elastic constant C′ and Young's modulus E agree well with that of the high-temperature strength. The critical temperature for ductility to brittleness is 850 °C. The matrix phase exhibits significantly brittleness character and increases slightly with decreasing temperature in single-phase paramagnetic (PM) γ-Fe region. The straightening zone temperature should be controlled above 950 °C to avoid cracks. In the austenite transition region, the drop rate of the magnetic moment reaches 18.90%. The findings suggest that the evolution law of mechanical properties of steels can be predicted from the elastic properties, especially during the austenite transition process, providing a basis for the prediction of material properties using ab initio methods.
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| 9. |
- Ai, S. -Y, et al.
(författare)
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High-temperature strength of l245mb slab and elastic properties of iron matrix
- 2019
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Ingår i: Kang T'ieh/Iron and Steel. - : Chinese Society for Metals. - 0449-749X. ; 54:8, s. 194-201
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Tidskriftsartikel (refereegranskat)abstract
- It‘s important to understand the evolution of high-temperature properties of slabs from the microscopic structure and the macroscopic structure, which is of great significance to the performance and quality control of slabs. The variation of the high-temperature strength of the L245MB slab with the temperature was measured by the hot tensile test technique with the Gleeble system. For the Fe matrix phase, which was under different crystal structures and magnetic states, the EMTO first-principles method was used to calculate the bulk modulus B, the single-crystal elastic constants c’ and c44, the polymorphic Young's modulus E, and the evolution of the system magnetic moment μ with temperature. The results showed that the cooling rate had little effect on the high-temperature strength evolution of the slab. The high-temperature strength took a transition near Ae3 and TC temperature, with a "platform" presented, where the average evolution rate of tensile strength was 0.008 Mpa/℃ and the yield strength was 0.076 Mpa/℃. The thermoplasticity of the slab had a different degree of decline in the temperature range of TC~Ae3, and the reduction of the area was the smallest at about 800℃, which was 59.02%~62.79%. The temperature range of ductility trough increased with the cooling rate increasing, and the surface temperature of the straightening zone should be controlled above 850 ℃ to avoid the crack generation. The elastic properties of the Fe matrix phase changed with the change of the magnetic state and the crystal structure. The transformation of the magnetic state had a greater influence on c’, c44, E, and the transformation of the crystal structure had a greater influence on B. During the transformation of FM to PM, c’ and E decreased by 64.09% and 10.33%, c44 increased by 57.82%, and B decreased by 34.38% with the change of bcc to fcc structure. The relationship between the evolution of single crystal elastic constant c’, polycrystalline Young's modulus E and the high-temperature strength of the slab were analyzed. It provides an idea for analyzing the macroscopic performance of the slab from the microstructural parameters of the crystal structure, which is a basis for the research and application of the first principles method in the high-temperature mechanical properties of steel materials.
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| 10. |
- Chen, Chenlin, et al.
(författare)
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Experimental and kinetic modeling study of laminar burning velocity enhancement by ozone additive in NH3+O2+N2 and NH3+CH4/C2H6/C3H8+air flames
- 2023
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 39:4, s. 4237-4246
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Tidskriftsartikel (refereegranskat)abstract
- Ammonia (NH3) is regarded as a promising future carbon-free fuel but needs to overcome drawbacks including extremely low burning velocity in practical combustion apparatus. In this study, ozone (O3) additive is used to elucidate one of the mechanisms of potential flame enhancement method based on plasma-assisted combustion. The effects of ozone addition on the laminar burning velocity of premixed NH3/(35%O2/65%N2) and NH3+ CH4/C2H6/C3H8+air flames over a wide range of equivalence ratios were investigated experimentally and numerically. Blending NH3 with hydrocarbons can decrease the ignition energy and increase the burning velocities of the whole mixture, which may contribute to developing ammonia co-fired mechanisms with varied complex fuels and validating the feasibility of NH3 using strategies in real applications. Measurements were conducted at atmospheric conditions using the Heat Flux method. For NH3/(35%O2/65%N2) flames, a significant increase was found on the fuel-lean side. Experimental data showed that maximum enhancement reaches 15.34% at π=0.6 with 5000 ppm O3 additive. For NH3+CH4/C2H6/C3H8+air blended flames, the enhancement effect was much more profound under off-stoichiometric conditions, being 1.5-4 times higher than that under near-stoichiometric conditions. A 28-step O3 related kinetic sub-mechanism was integrated with five selected NH3-oxidation mechanisms to simulate the burning velocities of NH3/(35%O2/65%N2) flames and CEU-Mech for NH3+CH4/C2H6/C3H8+air flames. Simulation results show improved agreement with the experimental data, especially for fuel-rich conditions as NH3 blending ratio xNH3 increases from 0 to 0.9. Each of the NH3/CH4/air, NH3/C2H6/air and NH3/C3H8/air cases fits well between experimental data and numerical results with varied NH3-fuel blending ratios. Detailed kinetic analyses adopting the CEU-NH3-Mech integrated with O3 sub-mechanism were carried out and revealed that active radicals such as HNO, which are rapidly produced due to high O concentration from O3 decomposing in the pre-heating zone, interfered with the ammonia-fuel chemistry and thus evidently promoted the overall combustion process.
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