In this work, a series of AlxCoFeNi and CoFeNiSix high-entropy alloys (HEAs) of different Al and Si molar ratio (x=0, 0.25, 0.5, 0.75 and 1)were designed and, the effects of Al and Si addition on the ...structure and properties of the materials was investigated by a systematic study on the phase, microstructure, mechanical behavior, electrical and magnetic properties. It was found that the amounts of Al and Si additions strongly influence the phase structures of the alloys; high molar ratio of Al element can change the FCC structure to BCC structure, while more Si addition can lead to new compounds. Both Al and Si addition can increase the yield strength and hardness with the sacrifice of plasticity and, the effect of adding Si on the mechanical properties is more significant than that of adding Al. Characterization of the magnetic properties and hysteresis loops revealed that, all these alloys show typical ferromagnetic behavior. The saturation magnetization decreases from 151.3emu/g (x=0) to 101.8emu/g (x=1) when changing the Al content; and decreases from 151.3emu/g (x=0) to 80.5emu/g (x=0.75) with changing the Si content. Si addition can decrease the saturation magnetization more significantly than Al addition. The opposite trend can be found in the effects of the alloying element on the electrical resistivity with varying Al or Si content, adding Si can increase the electrical resistivity from 16.7μΩcm to 82.89μΩcm. It was also found that, the alloys also undergo very small magnetostriction, which is essential to ensure that the materials are not stressed when an external magnetic field is applied (or conversely, that external stresses do not disrupt the magnetic properties).
•Multi-component AlxCoFeNi and CoFeNiSix high-entropy alloys are designed.•The Al or Si content strongly influences the phase structure.•Both Al and Si addition can increase the yield strength and reduce the ductility.•The alloys show high saturation magnetization and low coercivity.•Both alloy systems undergo small magnetostriction with the value lower than 35ppm.
Abstract
The interaction between the solar wind and the magnetosphere is one of the most important research subjects in the fields of astrophysics and space physics. For more than half a century, ...based on the pressure balance assumption between the solar wind and the magnetosphere and considering other important factors, such as the interplanetary magnetic field and magnetic reconnection process, the dynamic processes at the magnetopause have been extensively analyzed. However, the responses of magnetopause to the solar wind dynamic pressure variations are still complicated to understand. Here, we show that the interaction between the solar wind and the magnetosphere can be regarded as a quasi-elastodynamic process. The driving frequency of the solar wind is determined as a crucial reason for the phase difference between solar wind dynamic pressure variations and magnetopause standoff distance. The low-pass filter effect and oscillation properties of the magnetopause can also be well explained by the forced damped vibrations. Moreover, the quasi-elastodynamic processes predict deformations at the magnetopause, which resemble the magnetopause surface wave. Finally, a three-dimensional time-dependent magnetopause model is constructed and verified by observation. Based on 12,242 magnetopause crossing events, it is found that the new model reveals ∼9.7% better prediction accuracy than the widely used time-independent model. These results can also shed light on our understanding of the solar-wind–magnetopause interaction for other planets.
Although the sun is really far away from us, some solar activities could still influence the performance and reliability of space-borne and ground-based technological systems on Earth. Those ...time-varying conditions in space caused by the sun are also called solar storm or space weather. It is known that aviation activities can be affected during solar storms, but the exact effects of space weather on aviation are still unclear. Especially how the flight delays, the top topic concerned by most people, will be affected by space weather has never been thoroughly researched. By analyzing huge amount of flight data (~ 4 × 10
records), for the first time, we quantitatively investigate the flight delays during space weather events. It is found that compared to the quiet periods, the average arrival delay time and 30-min delay rate during space weather events are significantly increased by 81.34% and 21.45% respectively. The evident negative correlation between the yearly flight regularity rate and the yearly mean total sunspot number during 22 years also confirms such correlation. Further studies show that the flight delay time and delay rate will monotonically increase with the geomagnetic field fluctuations and ionospheric disturbances. These results indicate that the interferences in communication and navigation during space weather events may be the most probable reason accounting for the increased flight delays. The above analyses expand the traditional field of space weather research and could also provide us with brand new views for improving the flight delay predications.
Solar flares are one of the severest solar activities that have important effects on near-Earth space. Previous studies have shown that flight arrival delays increase as a result of solar flares, but ...the intrinsic mechanism behind this relationship is still unknown. In this study, we conducted a comprehensive analysis of flight departure delays during 57 solar X-ray events by using a huge amount of flight data (~ 5 × 10
records) gathered over a 5-year period. It is found that the average flight departure delay time during solar X-ray events increased by 20.68% (7.67 min) compared to quiet periods. Our analysis also revealed apparent time and latitude dependencies, with flight delays being more serious on the dayside than on the nightside and longer (shorter) delays tending to occur in lower (higher) latitude airports during solar X-ray events. Furthermore, our results suggest that the intensity of solar flares (soft X-ray flux) and the Solar Zenith Angle directly modulate flight departure delay time and delay rate. These results indicate that communication interferences caused by solar flares directly affect flight departure delays. This work expands our conventional understanding of the impacts of solar flares on human society and provides new insights for preventing or coping with flight delays.
Summary
Background
Recent work using genome–wide association studies (GWAS) in Chinese Han and white populations have discovered several novel psoriasis susceptibility genes.
Aim
To examine whether ...the risk loci for psoriasis identified in previous GWAS in a white population are also associated with psoriasis in a Chinese Uygur population in Xinjiang.
Methods
Genotyping analysis of eight single‐nucleotide polymorphisms (SNPs) associated with psoriasis was performed for 539 patients with psoriasis and 749 controls, all of Chinese Uygur descent, using a commercial assay.
Results
Two SNPs had an association with psoriasis in this Chinese Uygur population: SNP rs495337 in the gene encoding for zinc finger protein 313 (P < 0.001; OR = 0.80) and SNP rs20541 of the gene encoding for interleukin‐13 (P < 0.001; OR = 0.82). In subgroup analyses, the two SNPs were significantly associated (P < 0.05) with type I psoriasis, Rs495337 showed statistically difference between positive family history of psoriasis patients and controls whereas rs20541 might preferentially associated with negative family history psoriasis patients. Interestingly, using multifactor dimensionality reduction, a significant two‐locus interaction was seen between rs495337 and rs20541, with a crossvalidation consistency of 4/5 and average balanced prediction (accuracy 55.5%, P < 0.001).
Conclusions
ZNF313 and IL‐13 are associated with risk for psoriasis in a Chinese Uygur population, and there is an effect of interaction between the two genes on this risk.
Cables in large-scale fusion magnets are subjected to high transverse electromagnetic forces caused by high currents and magnetic fields. Consequently, they require sufficient mechanical strength to ...ensure safe and stable operation. To meet this requirement, a high-temperature superconducting (HTS) cable-in-conduit conductor (CICC) suitable for fusion reactors has been manufactured. Each conductor contains 10 round strands, and each strand is composed of a stack of 20 tapes (2 mm wide) surrounded by filling material (Sn 63 Pb 37 ) and a copper former. The conductor is further encased in a round stainless steel jacket to accommodate the large Lorentz forces. To investigate the degradation of the critical current ( I c ) under cyclic transverse loads, two prototype conductors, each approximately 1.4 m long, were fabricated using REBCO coated conductor tapes. Both conductors have the I c around 8.8 kA in self-field at 77 K. Additionally, cyclic transverse loading tests were performed at 77 K, self-field. The results revealed that the conductors were able to withstand large transverse loads (>200 MPa) with less than 5% degradation of the I c . However, a significant reduction in the I c (∼25%) was observed after 100 cycles, with the load amplitudes ranging from 20 MPa to 200 MPa. When the conductor was subjected to 500 to 10,000 cycles, no significant change in the I c was observed at ∼65% of its original value. Finally, to further understand and enhance the I c characteristics of the conductor, we investigated the defects caused by fabrication imperfections and mechanical loading microscopically. Our results will have significant implications for further improving the mechanical strength of the conductor and its application in fusion magnets.
An extraordinary high-strength dilute Mg-0.8Al-0.1Ca-0.6Mn (wt. %) alloy wire was successfully developed by hot drawing, which exhibits high tensile yield strength of 394 MPa, ultimate tensile ...strength of 431 MPa and moderate elongation to failure of 6.0%. The high strength was mainly attributed to the ultra-fine dynamically recrystallized (DRXed) grains, coarse elongated unrecrystallized grains with dense dislocations as well as nano-sized Al2Ca and Al–Mn precipitates dispersed in the as-drawn alloy wire. The microstructure observation by transmission electron microscopy reveals that Al and Ca remarkably co-segregated to the DRXed grain boundaries while Al rather than Ca segregated at the low-angle grain boundaries in the unrecrystallized grains. The solute segregations not only exerted strong solute drag effect on the grain boundaries to restrict the dynamic recrystallization and DRXed grain growth, but also contributed to the high strength of the alloy wire by pinning the dislocations. The findings from this work provide a new insight into the development of strong low-cost and light-weight Mg alloy wires.
To estimate the prevalence and incidence of diabetes mellitus and impaired glucose regulation (IGR) in a Chinese population aged 20-94 years.
A group of 5,628 randomly selected adults, aged 20-94 ...years, living in the Huayang and Caoyang communities in Shanghai, China, were investigated between 1998 and 2001. During 2002-04, 2,666 subjects were followed up. All the participants underwent anthropometric measurements, blood biochemical analyses and a 75-g OGTT.
Based on the 2000 census data of China, the age-standardised prevalences were 6.87% for diabetes and 8.53% for IGR at baseline. More than two in five cases with diabetes were undiagnosed. The age-adjusted prevalence of diabetes and IGR increased with age. The age-adjusted prevalences of hypertension, dyslipidaemia and overweight in males were significantly higher (p < 0.001) than in females. The 3-year cumulative incidence rates of diabetes and IGR were 4.96 and 11.10%, respectively. The relative risk of developing diabetes was significantly higher in subjects with IGR than in subjects with NGT (p < 0.001).
The prevalence and incidence rates for diabetes or IGR have increased dramatically over the last decades, especially in younger age groups. A large proportion of cases are undiagnosed. We strongly recommend that population-based diabetes screening programmes should be implemented and generalised for younger people.
The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10
electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV ...energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays
. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref.
). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane
, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.
Summary
Background
A previous study provided evidence for a genetic association between PPP2CA on 5q31.1 and systemic lupus erythematosus (SLE) across multi‐ancestral cohorts, but failed to find ...significant evidence for an association in the Han Chinese population.
Objectives
To explore the association between this locus and SLE using data from our previously published genome‐wide association study (GWAS).
Methods
Single‐nucleotide polymorphisms (SNPs) rs7726414 and rs244689 (near TCF7 and PPP2CA in 5q31.1) were selected as candidate independent associations from a large‐scale study in a Han Chinese population consisting of 1047 cases and 1205 controls. Subsequently, 3509 cases and 8246 controls were genotyped in two further replication studies. We then investigated the SNPs' associations with SLE subphenotypes and gene expression in peripheral blood mononuclear cells.
Results
Highly significant associations with SLE in the Han Chinese population were detected for SNPs rs7726414 and rs244689 by combining the genotype data from our previous GWAS and two independent replication cohorts. Further conditional analyses indicated that these two SNPs contribute to disease susceptibility independently. A significant association with SLE, age at diagnosis < 20 years, was found for rs7726414 (P = 0·001). The expression levels of TCF7 and PPP2CA messenger RNA in patients with SLE were significantly decreased compared with those in healthy controls.
Conclusions
This study found evidence for multiple associations with SLE in 5q31.1 at genome‐wide levels of significance for the first time in a Han Chinese population, in a combined genotype dataset. These findings suggest that variants in the 5q31.1 locus not only provide novel insights into the genetic architecture of SLE, but also contribute to the complex subphenotypes of SLE.
What's already known about this topic?
Systemic lupus erythematosus (SLE) is a prototype multisystem autoimmune inflammatory disease involving genetic and environmental predisposing factors.
Genome‐wide association studies have been performed to identify and confirm over 70 risk genes associated with SLE.
What does this study add?
This study confirmed two independent SLE association signals in 5q31.1, with genome‐wide levels of significance for the first time in a Han Chinese population.
Significant and suggestive associations were revealed between clinical manifestations and genetic variants.
Both TCF7 and PPP2CA are within the association interval and are very likely to be involved in the development of SLE.
What is the translational message?
The genetic variant in 5q31.1 contributes to the complex subphenotypes of SLE, which suggests that this variant can be a novel marker for SLE phenotypes.
The expression levels of TCF7 and PPP2CA messenger RNA in patients with SLE were significantly decreased, which suggests that TCF7 and PPP2CA can be used as an auxiliary method for the diagnosis of SLE.
Linked Comment: Sarin. Br J Dermatol 2017; 177:620–621
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