After 34 yr, the black hole candidate EXO 1846-031 went into outburst again in 2019. We investigate its spectral properties in the hard intermediate and the soft states with NuSTAR and Insight-HXMT. ...A reflection component has been detected in the two spectral states but possibly originating from different illumination spectra: in the intermediate state, the illuminating source is attributed to a hard coronal component, which has been commonly observed in other X-ray binaries, whereas in the soft state, the reflection is probably produced by disk self-irradiation. Both cases support EXO 1846-031 as a low-inclination system of . An absorption line is clearly detected at ∼7.2 keV in the hard intermediate state, corresponding to a highly ionized disk wind ( ) with a velocity of up to 0.06c. Meanwhile, quasi-simultaneous radio emissions have been detected before and after the X-rays, implying the coexistence of disk winds and jets in this system. If only the high-flux segment of the NuSTAR observation is considered, the observed wind appears to be magnetically driven. The absorption line disappeared in the soft state and a narrow emission line appeared at ∼6.7 keV on top of the reflection component, which may be evidence for disk winds, but data with higher spectral resolution are required to examine this.
Residual stress has a strong effect on the mechanical performance of coatings. To understand the mechanism of its generation and evolution in metastable alloy coatings, Ni-B alloy coatings with ...different degrees of crystallinity were prepared on 0.45% carbon steel substrate by an electro-brush plating technique. The amorphous proportion and grain size were investigated by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). With the help of the Lee model and Suresh model, residual stress in metastable state Ni-B alloy coating was determined from the load-displacement curves obtained by nanoindentation. From XRD and TEM results, the deposition was composed of amorphous and nanocrystalline phases, which contained compressive stress in the as-plated coatings. The compressive level decreased with the increase of annealing temperature. Compared with the Suresh model, Lee model is more suitable to evaluate residual stress in the metastable state materials. The experimental results also revealed that the compressive residual stress level was directly related to the total area of grain boundary.
Allergen-specific immunotherapy (ASIT) is the only allergic disease-modifying therapy available for children and adults, and recombinant allergens are an interesting approach to improve allergy ...diagnosis and ASIT. Tyrophagus putrescentiae is a common storage mite that produces potent allergens. The aim of this study was to express and characterize recombinant group 4 allergen protein of T. putrescentiae (Tyr p 4), and to further investigate allergenicity and potential epitopes of Tyr p 4.
The cDNA encoding Tyr p 4 was generated by RT-PCR and subcloned into pET-28a(+) plasmid. The plasmid was then transformed into E. coli cells for expression. After purification by nickel affinity chromatography and identification by SDS-PAGE, recombinant Tyr p 4 protein was used for a skin prick test and an ELISA to determine the allergic response.
Study participants’ allergic response rate to Tyr p 4 protein was 13.3% (16/120). Eight B-cell epitopes and three T-cell epitopes of Tyr p 4 were predicted.
Similar to group 4 allergens of other species of mite, allergenicity of Tyr p 4 is weak. The expression, characterization and epitope prediction of recombinant Tyr p 4 protein provide a foundation for further study of this allergen in the diagnosis and ASIT of storage mite allergy.
This study aims to assess the risk factors of cardiovascular disease (CVD) and to determine the association of traditional and biologic disease-modifying anti-rheumatic drugs (DMARDs) with risk for ...CVD in Chinese rheumatoid arthritis (RA) patients. A cross-sectional cohort of 2013 RA patients from 21 hospitals around China was established. Medical history of CVD was documented. The patients’ social background, clinical manifestations, comorbidities, and medications were also collected. Of the 2013 patients, 256 had CVD with an incidence of 12.7%. Compared with non-CVD controls, RA patients with CVD had a significantly advanced age, long-standing median disease duration, more often male and more deformity joints. Patients with CVD also had higher rates of smoking, rheumatoid nodules, interstitial lung disease, and anemia. The prevalence of comorbidities, including hypothyroidism, diabetes mellitus (DM), hypertension, and hyperlipidemia, was also significant higher in the CVD group. In contrast, patients treated with methotrexate, hydroxychloroquine (HCQ), and TNF blockers had lower incidence of CVD. The multivariate analysis showed that the use of HCQ was a protective factor of CVD, while hypertension, hyperlipidemia, and interstitial lung disease were independent risk factors of CVD. Our study shows that the independent risk factors of CVD include hypertension, hyperlipidemia, and interstitial lung disease. HCQ reduces the risk of CVD in patients with RA.
The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the Dark Matter Particle Explorer (DAMPE) is reported in this work. A ...hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of 4.3σ. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out.
ABSTRACT
Based on Insight-HXMT data, we report on the pulse fraction evolution during the 2017–2018 outburst of the newly discovered first Galactic ultraluminous X-ray (ULX) source Swift ...J0243.6+6124. The pulse fractions of 19 observation pairs selected in the rising and fading phases with similar luminosity are investigated. The results show a general trend of the pulse fraction increasing with luminosity and energy at supercritical luminosity. However, the relative strength of the pulsation between each pair evolves strongly with luminosity. The pulse fraction in the rising phase is larger at luminosity below 7.71 × 1038 erg s−1, but smaller at above. A transition luminosity is found to be energy independent. Such a phenomenon is first confirmed by Insight-HXMT observations and we speculate that it may have relation with the radiation-pressure-dominated accretion disc.
In this work, we report the in-orbit demonstration of X-ray pulsar navigation with Insight-Hard X-ray Modulation Telescope (Insight-HXMT) Satellite, which was launched on 2017 June 15. The new pulsar ...navigation method "Significance Enhancement of Pulse-profile with Orbit-dynamics" is adopted to determine the orbit with observations of only one pulsar. In this test, the Crab pulsar is chosen and observed by Insight-HXMT from 2017 August 31 to September 5. Using the five-day long observation data, the orbit of Insight-HXMT is determined successfully with the three telescopes onboard: High Energy X-ray Telescope, Medium Energy X-ray Telescope, and Low Energy X-ray Telescope, respectively. By combining all the data, the position and velocity of the Insight-HXMT are pinpointed to within 10 km (3 ) and 10 m s−1 (3 ), respectively.
•MTs were introduced into the Ni-Co base superalloy by pre-strain treatment, which enhance the mechanical properties.•After pre-strain treatment, the YS at 23 °C increased by 19.5%, the YS at 760 °C ...increased by 16.5%.•The creep life is reduced by pre-strain, even if it improved slightly when treatment time increases from 50 h to 100 h.•Impediment of MT to the motion of dislocations is the reason for the better mechanical properties.•Introduction of MT appropriately can be considered as a novel strengthening method in designing advanced superalloy.
The effect of pre-strain treatment on mechanical properties of a Ni-Co base disk superalloy was studied. Results show that the pre-strain treatment, creep at 725 °C/630 MPa, improves the yield strength of the alloy at 23 °C and 760 °C. However, the creep life (at 760 °C/480 MPa) of the alloy was reduced by pre-strain treatment. The microstructure indicated that a lot of microtwins and Suzuki segregations were introduced by the pre-strain treatment, besides some unfavorable factors on mechanical properties, i.e., ripening of precipitates. The interactions of microtwin and Suzuki segregation with dislocations were discussed in this study, and it was deemed that the impediment of twin boundary and Suzuki segregation to the motion of dislocation may be responsible for the enhancement of the mechanical properties. Meanwhile, the microtwin and the Suzuki segregation have good stability at service temperature. If the problem of reducing the creep properties caused by pre-strain treatment would be solved, the introduction of microtwin and Suzuki segregation appropriately can be considered as a novel strengthening method in designing advanced superalloys.
The band topology of a new half-Heusler family with 8 valence electrons composed of light elements is investigated by the first-principle calculations. Many of these compounds are predicted to be ...topological insulators. The new topological insulators exhibit great band inversion strength (up to −2.56 eV). Both the occurrence of the band inversion and the opening topological insulating gap can be performed only by the strain engineering. Based on these results, we also argue that the spin–orbit coupling effect is not an essential factor in the band inversion and the formation of topological insulating gap.
•A family of TIs composed of light elements was reported.•The new TIs exhibit a great band inversion strength.•SOC effect is unessential to open the insulating gap and inverse the band order.•The band inversion and the insulating gap can occur as long as a strain is applied.
ABSTRACT
We report on our analysis of the 2019 outburst of the X-ray accreting pulsar 4U 1901+03 observed with Insight-HXMT and NICER. Both spectra and pulse profiles evolve significantly in the ...decaying phase of the outburst. Dozens of flares are observed throughout the outburst. They are more frequent and brighter at the outburst peak. We find that the flares, which have a duration from tens to hundreds of seconds, are generally brighter than the persistent emission by a factor of ∼1.5. The pulse-profile shape during the flares can be significantly different from that of the persistent emission. In particular, a phase shift is clearly observed in many cases. We interpret these findings as direct evidence of changes of the pulsed beam pattern, due to transitions between the sub- and supercritical accretion regimes on a short time-scale. We also observe that at comparable luminosities the flares’ pulse profiles are rather similar to those of the persistent emission. This indicates that the accretion on the polar cap of the neutron star is mainly determined by the luminosity, i.e. the mass accretion rate.
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