| 1. |
- Cheng, Q., et al.
(författare)
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Unveiling anneal hardening in dilute Al-doped AlxCoCrFeMnNi (x=0, 0.1) high-entropy alloys
- 2021
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Ingår i: Journal of Materials Science & Technology. - : Elsevier BV. - 1005-0302. ; 91, s. 270-277
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Tidskriftsartikel (refereegranskat)abstract
- Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic (FCC) structure, whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature (T-rx). Microscopically, this hardening effect has been ascribed to several mechanisms, i.e. solute segregation to defects (dislocation and stacking fault) and short-range chemical ordering, etc. However, none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys (HEAs). Here we report the observations, using high-resolution electron channeling contrast imaging and transmission electron microscopy, of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T-rx. The dislocation substructures are observed to be thermally stable up to T-rx, which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation occurs. The microstructure feature is markedly different from that of conventional dilute solid solution alloys, in which dislocation substructures gradually vanish by recovery during annealing, leading to a strength drop. Furthermore, dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed (<= 500 degrees C) HEA. This Al induced softening effect, could be associated with the anisotropic formation of dislocation substructure, resulting from enhanced dislocation planar slip due to glide plane softening effect. These findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening.
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| 2. |
- Cheng, Q., et al.
(författare)
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Solid solution softening in a Aloi CoCrFeMnNi high-entropy alloy
- 2020
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 186, s. 63-68
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Tidskriftsartikel (refereegranskat)abstract
- Solute effects on high-entropy alloys of equiatomic proportions are scientifically intriguing because there is no such well-defined "solute" and "solvent" atoms compared to those of conventional single principal element alloys. To date, most of the face-centered cubic alloys exhibit solid solution strengthening rather than softening due to the interactions between dislocations and solute atoms. Here, we present the careful experimental measurements and demonstrate solid solution softening, albeit weak, in a single phase CoCrFeMnNi through the minor addition of 2. at.% Al. This softening effect is mostly related to the decreased Peierl's stress by Al addition.
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| 3. |
- Lei, Xiaoqin, et al.
(författare)
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A generalized interpolation material point method for modelling coupled thermo-hydro-mechanical problems
- 2021
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier BV. - 0045-7825. ; 386
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a Generalized Interpolation Material Point Method (GIMP) for modelling coupled thermo-hydro-mechanical (THM) processes within unsaturated porous media. The governing equations for the coupled thermo-hydro-mechanical problems are derived based on the conservation laws of mass, momentum and energy, and are discretized within the framework of the explicit three-phase single-point GIMP. The proposed THM-coupled GIMP is validated against available analytical solutions and FEM-based numerical solutions, and is used for simulating a climate-driven slope failure process involving both temperature variation and rainfall infiltration. The proposed THM-coupled GIMP is proved to be capable to capture the fully coupled thermo-hydro-mechanical process within unsaturated porous media associated with large deformations.
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| 4. |
- Li, Xiaoqing, et al.
(författare)
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Antihyperuricemic Effect of Green Alga Ulva lactuca Ulvan through Regulating Urate Transporters
- 2021
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 69:38, s. 11225-11235
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Tidskriftsartikel (refereegranskat)abstract
- A novel polysaccharide from Ulva lactuca (ULP) was purified using a Sepharose CL-4B column. Fourier transform infrared spectroscopy, high-performance liquid chromatography, and nuclear magnetic resonance spectroscopy were employed to analyze the structure of ULP. It consisted of rhamnose (Rha), glucuronic acid (GluA), galactose (Gal), and xylose (Xyl) at a molar ratio of 32.75:22.83:1.07:6.46 with the molecular weight of 2.24 x 10(5) Da. The four major glycosidic residues found in ULP were -> 2,3)-alpha-L-Rhap-(1 ->, -> 4)-beta-D-GlcpA-(1 ->, -> 2,6)-beta-D-Galp-(1 ->, and -> 4)-beta-D-Xylp-(1 ->. The antihyperuricemic activity of ULP was exhibited by detecting related biochemical indexes, urate transporter gene expressions, renal histopathology, and intestinal microbiota shifts. ULP obviously decreased the levels of serum uric acid (UA), blood urea nitrogen, and creatinine, while inhibited serum and hepatic xanthine oxidase activities as well as improved renal injury in hyperuricemic mice. Furthermore, the upregulation of UA excretion genes ABCG2/OAT1 and downregulation of UA resorption genes URAT1 and GLUT9 were detected. In addition, ULP exerted its antihyperuricemic effect through regulating the intestinal microbiome, characterized by elevating the helpful microbial abundance, meanwhile declining the harmful bacterial abundance and restoring the gut microbiome homeostasis. This study demonstrates the antihyperuricemic activity of ULP and its potential effect for the treatment of hyperuricemia-related diseases.
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| 5. |
- Qin, Gang, et al.
(författare)
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An as-cast high-entropy alloy with remarkable mechanical properties strengthened by nanometer precipitates
- 2020
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Ingår i: Nanoscale. - : ROYAL SOC CHEMISTRY. - 2040-3364 .- 2040-3372. ; 12:6, s. 3965-3976
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Tidskriftsartikel (refereegranskat)abstract
- High-entropy alloys (HEAs) with good ductility and high strength are usually prepared by a combination of forging and heat-treatment processes. In comparison, the as-cast HEAs typically do not reach strengths similar to those of HEAs produced by the forging and heat-treatment processes. Here we report a novel equiatomic-ratio CoCrCuMnNi HEA prepared by vacuum arc melting. We observe that this HEA has excellent mechanical properties, i.e., a yield strength of 458 MPa, and an ultimate tensile strength of 742 MPa with an elongation of 40%. Many nanometer precipitates (5-50 nm in size) and domains (5-10 nm in size) are found in the inter-dendrite and dendrite zones of the produced HEA, which is the key factor for its excellent mechanical properties. The enthalpy of mixing between Cu and Mn, Cr, Co, or Ni is higher than those of mixing between any two of Cr, Co, Ni and Mn, which leads to the separation of Cu from the CoCrCuMnNi HEA. Furthermore, we reveal the nanoscale-precipitate-phase-forming mechanism in the proposed HEA.
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| 6. |
- Qin, Gang, et al.
(författare)
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Experimental and theoretical investigations on the phase stability and mechanical properties of Cr7Mn25Co9Ni23Cu36 high-entropy alloy
- 2021
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 208
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the mechanisms of phase formation and their influence on the mechanical behavior is crucial for materials used in structural applications. Here, the phase decomposition under heat treatment in the Cr7Mn25Co9Ni23Cu36 (atomic percentage) high-entropy alloy and how secondary phases formed affect its tensile mechanical response are reported. The microstructural analysis shows that heat treatment at 800 degrees C /2 h and 600 degrees C /8 h led to the formation of sigma phase, but the sigma phase was not observed for 2 h heat treatment at 600 degrees C and below. The experimentally observed thermal stability and phases are compared to the calculated phase diagram and rationalized by recourse to thermodynamics and kinetics. The mechanism of phase decomposition is discussed based on ab initio calculations, indicating that decomposition into two solid solution phases is energetically preferred over a single solid solution phase with nominal composition.
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| 7. |
- Wang, Xiaoqing, et al.
(författare)
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Inhibiting the aberrant activation of Wnt/β-catenin signaling by selenium supplementation ameliorates deoxynivalenol-induced toxicity and catabolism in chondrocytes
- 2020
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Ingår i: Journal of Cellular Physiology. - : Wiley-Blackwell. - 0021-9541 .- 1097-4652. ; 235:5, s. 4434-4442
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Tidskriftsartikel (refereegranskat)abstract
- Kashin-Beck disease (KBD) is an endemic degenerative osteoarticular disorder associated with physical disability and a heavy economic burden. Contamination by mycotoxin deoxynivalenol (DON) and selenium deficiency have been proposed to be key etiological factors for KBD, and can work together to aggravate the progression of KBD. Nevertheless, the mechanism of DON in KBD remains elusive. In the present study, exposure to DON dose-dependently suppressed cell viability and expression of pro-proliferation marker PCNA in human chondrocytes, whereas it enhanced lactate dehydrogenase release, cell apoptosis, and caspase-3/9 activity. In addition, DON incubation shifted metabolism homeostasis towards catabolism by suppressing the transcription of collagen II and aggrecan, and the production of sulphated glycosaminoglycans and TIMP-1, while increasing matrix metalloproteinase levels (MMP-1 and MMP-13). Mechanistically, DON exposure induced the activation of Wnt/β-catenin signaling. Intriguingly, blocking this pathway reversed the adverse effects of DON on cytotoxic damage and metabolism disruption to catabolism. Notably, supplementation with selenium reduced DON-induced activation of the Wnt/β-catenin pathway. Moreover, selenium addition abrogated cytotoxic injury and excessive pro-catabolic gene expression in chondrocytes upon DON conditions. These findings confirm that DON may facilitate the development of KBD by inducing cell injury, inhibiting matrix synthesis, and increasing cellular catabolism by activating the Wnt/β-catenin signaling, which were partially reversed by selenium supplementation. Thus, the current study may presents a new viewpoint for how selenium supplementation ameliorates the development of KBD by inhibiting DON-induced cytotoxic injury and metabolism imbalance in chondrocytes.
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| 8. |
- Yu, Qiang, et al.
(författare)
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Unveiling segregation-induced evolution in phase constitution of Cu-containing high-entropy alloys
- 2020
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 843
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical investigation of Cu segregation effect on phase constitution, magnetic, and mechanical properties of FeCoNi(CumAl)(x) high-entropy alloys is presented. Results show that the homogenous FeCoNi(Cu1.0Al)(x) only exists as a single face-centered cubic phase at arbitrary temperatures. The level of Cu-segregation determines the phase evolution amongst inhomogeneous single phase (0.75 <= m < 1.0), duplex phase (m << 0.75), and triple phase (m approximate to 0.75). Our results reproduce the observation. Only face-centered cubic phase can be formed for FeCoNi(CumAl)(x) with either rather low or extreme high content of (CumAl) even though the segregation occurred. The Cu addition lifts the total magnetic moments by enhancing the local magnetic moment of Fe, Co and Ni. The serious Cu segregation in the duplex-phase HEAs induces the decrease of ductility of fcc and bcc phases. The increasing Cu enhances the strength of Cu-rich fcc phase and the decreasing Cu weakens that of Cu-poor bcc phase.
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| 9. |
- Zhou, Sirui, et al.
(författare)
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A Neanderthal OAS1 isoform protects individuals of European ancestry against COVID-19 susceptibility and severity
- 2021
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Ingår i: Nature Medicine. - : Springer Nature. - 1078-8956 .- 1546-170X. ; 27:4, s. 659-667
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Tidskriftsartikel (refereegranskat)abstract
- To identify circulating proteins influencing Coronavirus Disease 2019 (COVID-19) susceptibility and severity, we undertook a two-sample Mendelian randomization (MR) study, rapidly scanning hundreds of circulating proteins while reducing bias due to reverse causation and confounding. In up to 14,134 cases and 1.2 million controls, we found that an s.d. increase in OAS1 levels was associated with reduced COVID-19 death or ventilation (odds ratio (OR) = 0.54, P = 7 × 10−8), hospitalization (OR = 0.61, P = 8 × 10−8) and susceptibility (OR = 0.78, P = 8 × 10−6). Measuring OAS1 levels in 504 individuals, we found that higher plasma OAS1 levels in a non-infectious state were associated with reduced COVID-19 susceptibility and severity. Further analyses suggested that a Neanderthal isoform of OAS1 in individuals of European ancestry affords this protection. Thus, evidence from MR and a case–control study support a protective role for OAS1 in COVID-19 adverse outcomes. Available pharmacological agents that increase OAS1 levels could be prioritized for drug development.
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