Increasing the density of sinks such as grain boundaries and interfaces for irradiation-induced defects and implanted ions has been demonstrated to be an effective way to improve the irradiation ...resistance of materials. To understand the effects of grain boundaries on the degradation mechanism of nanostructured materials, nanocrystalline tungsten was fabricated by high pressure torsion (HPT-W). Morphological changes of HPT-W and coarse grain tungsten (CG-W) during helium ion irradiation were evaluated in situ in a helium ion microscopy. It has been shown that the degradation mechanisms of CG-W and HPT-W are remarkably different. Blister occurs on the surface of CG-W when the irradiation dose increases up to 5.0 × 1021 m−2, and orientation dependence of blistering has been observed. However, no blister is formed on the surface of HPT-W even when the irradiation dose increases up to 1.0 × 1023 m−2. Instead, crack formation along grain boundaries is the major degradation mechanism during helium irradiation of HPT-W, supporting a different irradiation degradation mechanism. This explains the unprecedented irradiation tolerance of HPT-W in terms of blistering. Molecular dynamics results also show that grain boundaries and helium clusters play an important role during the propagation of a crack. The zigzag crack planes are attributed to the coalescence and growth of helium blister/bubble-induced crack. The results document that grain boundaries play decisive roles in the irradiation resistance of nanostructured materials, and provide a new perspective to the design of plasma facing materials with excellent irradiation resistance. It is thus suggested that excellent irradiation resistance can be achieved by a meticulous design of grain boundaries based on “interface engineering”.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The regioselective ring‐opening of 1,2‐ and 1,3‐sulfamidates with fluorine anion is reported. Direct construction of monofluoro‐substituted amines and amino acid derivatives using inexpensive and ...easily available potassium fluoride (KF). The monofluorination process only needs 35 minutes under heating, which will be an attractive route for the synthesis of the PET fluorine‐18 radiotracer. The application of the product can be extended to the construction of fluorinated polypeptides after simple deprotection treatment.
The regioselective ring‐opening of 1,2‐ and 1,3‐sulfamidates with fluorine anion is reported. Construction of monofluoro‐substituted amines and amino acid derivatives is realized by using inexpensive potassium fluoride (KF). The monofluorination process only needs 35 minutes under heating, which will be an attractive new route for the synthesis of the PET fluorine‐18 radiotracer.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Objectives
To evaluate the effectiveness of the Chinese version of the Montreal Cognitive Assessment Basic (MoCA‐BC) as a screening tool for detecting mild cognitive impairment (MCI) in Chinese ...elderly adults.
Design
Cross‐sectional.
Setting
Huashan Hospital, Shanghai, China.
Participants
Individuals with MCI (n = 264) and mild Alzheimer's disease (AD) (n = 160) were recruited from the Memory Clinic, Huashan Hospital; cognitively normal controls were recruited from Jinshan Community, Shanghai, China (n = 280).
Measurements
MoCA‐BC scores.
Results
The MoCA‐BC had good criterion‐related validity (Pearson correlation coefficient MoCA‐BC vs MMSE = 0.787) and reliable internal consistency (Cronbach alpha = 0.807). The optimal cutoff scores for MCI screening were 19 for individuals with no more than 6 years of education, 22 for individuals with 7 to 12 years of education, and 24 for individuals with more than 12 years of education. The MoCA‐BC was superior to the MMSE for detecting MCI, with optimal sensitivity and specificity across all education groups using the above cutoff scores.
Conclusion
The MoCA‐BC is a reliable cognitive screening test across all education levels in Chinese elderly adults, with high acceptance and good reliability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We have investigated the segregation, trapping and diffusion of He in a ∑3 {111} W grain boundary (GB) using combined techniques of ab initio and classical atomistic simulations. We show that, with ...an average segregation energy of −3.20 eV, the strong He trapping can be attributed to a GB interstitial trapping or a vacancy trapping mechanism, while an average energy barrier of 1.97 eV leads to a slow diffusion of He in the GB plane. We further reveal by molecular dynamics simulations that the He diffusion will be dictated by GB migration through the motion of GB disconnections. Interestingly, we also observe a He-induced GB structural transition in classical simulations. The present work suggests that the GB does not provide fast transport channel for He, providing useful reference for the possible application of polycrystalline W under He irradiation in advanced nuclear fusion reactors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We performed constant-potential molecular dynamics simulations to analyse the double-layer structure and capacitive performance of supercapacitors composed of conductive metal-organic framework (MOF) ...electrodes and ionic liquids. The molecular modelling clarifies how ions transport and reside inside polarized porous MOFs, and then predicts the corresponding potential-dependent capacitance in characteristic shapes. The transmission line model was adopted to characterize the charging dynamics, which further allowed evaluation of the capacitive performance of this class of supercapacitors at the macroscale from the simulation-obtained data at the nanoscale. These 'computational microscopy' results were supported by macroscopic electrochemical measurements. Such a combined nanoscale-to-macroscale investigation demonstrates the potential of MOF supercapacitors for achieving unprecedentedly high volumetric energy and power densities. It gives molecular insights into preferred structures of MOFs for accomplishing consistent performance with optimal energy-power balance, providing a blueprint for future characterization and design of these new supercapacitor systems.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The harsh irradiation environment poses serious threat to the structural integrity of leading candidate for plasma-facing materials, tungsten (W), in future nuclear fusion reactors. It is thus ...essential to understand the radiation-induced segregation of native defects and impurities to defect sinks, such as grain boundaries (GBs), by quantifying the segregation energetics. In this work, molecular statics simulations of a range of equilibrium and metastable 100 symmetric tilt GBs are carried out to explore the energetics of vacancy segregation. We show that the low-angle GBs have larger absorption length scales over their high-angle counterparts. Vacancy sites that are energetically unfavorable for segregation are found in all GBs. The magnitudes of minimum segregation energies for the equilibrium GBs vary from -2.61 eV to -0.76 eV depending on the GB character, while those for the metastable GB states tend to be much lower. The significance of vacancy delocalization in decreasing the vacancy segregation energies and facilitating GB migration has been discussed. Metrics such as GB energy and local stress are used to interpret the simulation results, and correlations between them have been established. This study contributes to the possible application of polycrystalline W under irradiation in advanced nuclear fusion reactors.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Systematic energetics analysis on the shape preference, relative stability and radiation-induced segregation of interstitial loops in nickel-containing single-phase concentrated solid-solution alloys ...have been conducted using atomistic simulations. It is shown that the perfect loops prefer rhombus shape for its low potential energy, while the Frank faulted loops favor ellipse for its low potential energy and the possible large configurational entropy. The decrease of stacking fault energy with increasing compositional complexity provides the energetic driving force for the formation of faulted loops, which, in conjunction with the kinetic factors, explains the experimental observation that the fraction of faulted loops rises with increasing compositional complexity. Notably, the kinetics is primarily responsible for the absence of faulted loops in nickel-cobalt with a very low stacking fault energy. We further demonstrate that the simultaneous nickel enrichment and iron/chromium depletion on interstitial loops can be fully accounted for by their energetics.
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•The shape preference of interstitial loops in SP-CSAs is investigated.•Stacking fault energy and the kinetics factors significantly affect the formation of faulted loops.•Radiation-induced segregation on interstitial loops is explained.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
To verify the inhibitory mechanism of β‐catenin‐designed peptides in colorectal cancer(CRC) tumors, the following experiments were performed. In vitro colony formation, Transwell assays, and flow ...cytometry were performed to assess the biological effects of designed peptides (F18KD, F20A4‐7k, F20A4‐10k, and F20A3‐9k + F20A4‐10k + F20A5‐9k) in HT‐29 cells. In vivo xenograft experiments were performed and treated with peptides. Next, tumors were subjected to Hematoxylin and eosin staining (HE), immunohistochemical, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining assays to evaluate the inhibitory effect of peptides on tumors. β‐Catenin levels were quantified via western blotting (WB) and quantitative real‐time polymerase chain reaction, and β‐catenin was located using confocal laser scanning microscopy. T‐cell factor‐4 (TCF‐4), C‐myc, and CCND1 levels were quantified via WB. Results were obtained as following. First, the peptides reduced viability, migration, and invasion; promoted apoptosis; and stabilized the S phase of HT‐29 cells. Second, peptides suppressed tumor growth and downregulated the expression of CD34, vascular endothelial growth factor, and β‐catenin in tumors. Furthermore, we found that peptides downregulated β‐catenin expression in both the cytoplasm and nucleus; TCF‐4, C‐myc, and CCND1 expression was also downregulated. Notably, β‐catenin‐targeting peptides had a better inhibitory effect on CRC than non‐β‐catenin‐target peptides, and a combination of peptides exerted a more potent inhibitory effect on CRC than single peptides. It suggested that β‐Catenin‐targeting peptides promote apoptosis in CRC tumors by inhibiting activation of the Wnt/β‐catenin pathway.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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