ABSTRACT
We report the evolution of the X-ray pulsations of EXO 2030+375 during its 2021 outburst using the observations from Insight-HXMT. Based on the accretion torque model, we study the ...correlation between the spin frequency derivatives and the luminosity. Pulsations can be detected in the energy band of 1–160 keV. The pulse profile evolves significantly with luminosity during the outburst, leading to that the whole outburst can be divided into several parts with different characteristics. The evolution of the pulse profile reveals the transition between the supercritical (fan-beam dominated) and the subcritical accretion (pencil-beam dominated) mode. From the accretion torque model and the critical luminosity model, based on a distance of 7.1 kpc, the inferred magnetic fields are (0.41 − 0.74) × 1012 and (3.48 − 3.96) × 1012 G, respectively, or based on a distance of 3.6 kpc, the estimated magnetic fields are (2.4 − 4.3) × 1013 and (0.98 − 1.11) × 1012 G, respectively. Two different sets of magnetic fields both support the presence of multipole magnetic fields of the neutron star.
Two brown-like adipocytes, including classical brown adipocytes from brown adipose tissues and beige cells from white adipose tissues, regulate thermogenesis. The developmental and functional ...induction of brown-like cells provides a defense against obesity and associated metabolic diseases. Our previous study suggests dietary luteolin can improve diet-induced obesity and insulin resistance in mice. Here we further elucidated the action of the natural flavonoid on energy expenditure and adaptive thermogenesis.
Five-week-old male C57BL/6 mice were fed low-fat diet (LFD), high-fat diet (HFD) and HFD supplemented with 0.01% luteolin. After 12 weeks, their energy expenditure were detected using a combined indirect calorimetry system. Moreover, thermogenic program and associated molecular regulators were assessed in adipose tissues. In another independent study, even-aged mice were fed LFD and luteolin-containing LFD for 12 weeks, and their energy expenditure and thermogenic program were also investigated. Finally, differentiated primary brown and subcutaneous adipocytes were used to identify the critical participation of AMPK/PGC1α signaling in luteolin-regulated browning and thermogenesis.
In mice fed either HFD or LFD, dietary luteolin supplement increased oxygen consumption, carbon dioxide production and respiratory exchange ratio. The enhancement in energy expenditure was accompanied by the upregulation of thermogenic genes in brown and subcutaneous adipose tissues. Meanwhile, several important AMPK/PGC1α signaling molecules were activated by dietary luteolin in the tissues. Further, luteolin treatment directly elevated thermogenic gene expressions and activated AMPK/PGC1α signaling in differentiated primary brown and subcutaneous adipocytes, whereas AMPK inhibitor Compound C reversed the efficiencies.
Dietary luteolin activated browning and thermogenesis through an AMPK/PGC1α pathway-mediated mechanism.
•The multi-fold binary Darboux transformation for a three-component Gross-Pitaevskii system are presented.•We derive three new types of exponential-and-rational mixed soliton solutions.•Interaction ...mechanisms between the mixed and exponential solitons are classified in the six cases.
The Bose-Einstein-condensation applications give rise to the superfluidity in the liquid helium and superconductivity in the metals. In this paper, we work on a three-component Gross-Pitaevskii system, which describes the matter waves in an spin-1 spinor Bose-Einstein condensate. We construct a multi-fold binary Darboux transformation with the zero seed solutions to describe the three vertical spin projection of the spin-1 spinor BEC, which is different from all the existing Darboux-type ones for the same system, and derive three types of the exponential-and-rational mixed soliton solutions associated with two conjugate complex eigenvalues. For such mixed solitons, we give their asymptotic expressions, indicating that they consist of the Ieda-Miyakawa-Wadati (IMW)-polar-state or IMW-ferromagnetic solitons but possess the time-dependent velocities. Asymptotically and graphically, interaction mechanisms between the mixed and exponential solitons are classified in six cases, and we exhibit the inelastic and elastic interactions through calculating the modifications of the polarization matrices and phase shifts for the two interacting solitons. We find that both the IMW-polar-state solitons, including the mixed and exponential solitons, can not alter the other soliton’s intensity distribution during the interaction, while the mixed or exponential soliton in the IMW-ferromagnetic state does.
Abstract
The fast transitions between different types of quasi-periodic oscillations (QPOs) are generally observed in black hole transient sources (BHTs). We present a detailed study of the timing ...and spectral properties of the transitions of type-B QPOs in MAXI J1348–630, observed by Insight-HXMT. The fractional rms variability–energy relationship and energy spectra reveal that type-B QPOs probably originate from jet precession. Compared to a weak power-law dominated power spectrum, when type-B QPOs are present, the corresponding energy spectrum shows an increase in the Comptonization component and the need for the
xillverCp
component, and a slight increase in the height of the corona when using the
relxilllp
model. Therefore, we suggest that a coupled inner disk-jet region is responsible for the observed type-B QPO transitions. The timescale for the appearance/disappearance of type-B QPOs is either long or short (seconds), which may indicate instability of the disk-jet structure. For these phenomena, we hypothesize that the Bardeen–Petterson effect causes the disk-jet structure to align with the BH spin axis or that the disappearance of small-scale jets bound by the magnetic flux tubes leads to the disappearance of type-B QPOs. We observed three events regarding the B/C transitions, one of which occurred over a short time period from ∼9.2 Hz (C) to ∼4.8 Hz (B). The energy spectral analysis for the other two transitions shows that when type-C QPO is present, the Comptonization flux is higher, the spectrum is harder, and the inner radius of the disk changes insignificantly. We suggest that type-C QPOs probably originate from relatively stronger jets or the corona.
Acute myeloblastic leukemia (AML) is characterized by the accumulation of abnormal myeloblasts (mainly granulocyte or monocyte precursors) in the bone marrow and blood. Though great progress has been ...made for improvement in clinical treatment during the past decades, only minority with AML achieve long-term survival. Therefore, further understanding mechanisms of leukemogenesis and exploring novel therapeutic strategies are still crucial for improving disease outcome. MicroRNA-100 (miR-100), a small non-coding RNA molecule, has been reported as a frequent event aberrantly expressed in patients with AML; however, the molecular basis for this phenotype and the statuses of its downstream targets have not yet been elucidated. In the present study, we found that the expression level of miR-100 in vivo was related to the stage of the maturation block underlying the subtypes of myeloid leukemia. In vitro experiments further demonstrated that miR-100 was required to promote the cell proliferation of promyelocytic blasts and arrest them differentiated to granulocyte/monocyte lineages. Significantly, we identified RBSP3, a phosphatase-like tumor suppressor, as a bona fide target of miR-100 and validated that RBSP3 was involved in cell differentiation and survival in AML. Moreover, we revealed a new pathway that miR-100 regulates G1/S transition and S-phase entry and blocks the terminal differentiation by targeting RBSP3, which partly in turn modulates the cell cycle effectors pRB/E2F1 in AML. These events promoted cell proliferation and blocked granulocyte/monocyte differentiation. Our data highlight an important role of miR-100 in the molecular etiology of AML, and implicate the potential application of miR-100 in cancer therapy.
Solar cooling technology is environmentally friendly and contributes to a significant decrease of the CO2 emissions which cause the green house effect. Currently, most of the solar cooling systems ...commonly used are the hot water driven lithium bromide absorption chillers. According to the operating temperature range of driving thermal source, single-effect LiBr/H2O absorption chillers have the advantage of being powered by ordinary flat-plate or evacuated tubular solar collectors available in the market. In this paper, besides the review of the existing theoretical and experimental investigations of solar single-effect absorption cooling systems, some new design options with regard to solar collectors, auxiliary energy systems and cooling modes were introduced. And then, other main types of solar absorption cooling systems based on double-effect, half-effect and two-stage absorption chillers were summarized. For buildings with high amounts of cooling load and limited installation area, solar-powered double-effect absorption cooling systems may be considered on condition that the direct irradiation is high enough. Half-effect absorption chillers and two-stage absorption chillers seem to be more suitable for air-cooled solar absorption cooling systems in hot and dry regions which are short of water. It is highly recommended to study the standardised design guidelines according to different areas for the purpose of widespread applications of solar cooling systems.
This study investigates the effect of annealing treatment on the phase transformation and mechanical properties of the equiatomic TiZrNbTa MEA from room temperature to 1200 °C. After annealing at ...1200 °C for 24h, the single solid-solution body-centred cubic (BCC) phase in the as-cast Ta25Zr25Nb25Ti25 transformed into an extremely high number density (~103/μm2) of Ta–Nb-rich BCC nanocuboidal phase (28 ± 10 nm square, BCC1) and a nanostrip-like Zr-rich BCC phase (3 ± 2 nm thick, BCC2). The phase separation from BCC to BCC1 and BCC2 arises from two primary reasons: (i) the high positive mixing enthalpy of both Ta–Zr and Nb–Zr (strong tendency to separation between each pair), and (ii) the 3–4 orders of magnitude higher mobility of Zr than Ta, Nb and Ti in these MEAs (kinetically driven). Detailed CALPHAD simulations of phase formation in this MEA agreed with experiments and provided insightful phase transformation details. The calculated diffusion distance of Zr (~4.1 nm) from the CALPHAD data corresponds to the measured Zr-rich nanostrip thickness (3 ± 2 nm). The nanocuboidal BCC1-BCC2 structure exhibited 112 -type of twinning deformation under compression at room temperature. The Ta25Zr25Nb25Ti25 MEA retained yield strength of ~410 MPa at 1000 °C and ~210 MPa at 1200 °C. The phase transformation during cooling after annealing and the microstructural evolution during compression at temperatures from 600 °C to 1200 °C were characterized and discussed in detail.
This study presents the effects of Zr addition on microstructure, phase composition, and superelasticity of Ti-24Nb-xZr (at.%, x = 0, 2, 6) alloys fabricated by spark plasma sintering (SPS). The ...obtained microstructures were studied using X-ray diffraction and electron microscopy, and the mechanical properties and shape memory properties were evaluated through both compressive testing and cyclic compression experiments. The results show the addition of Zr is beneficial to the formation of the α’’ phase and β-Ti grain refinement. The sintered Ti-24Nb-6Zr shows better compressive yield strength (1457 MPa), ultimate strength (2458 MPa), and strain (45.31%). Cycle compression tests reveals that the Ti-24Nb-6Zr alloy demonstrates stable recoverable strain of 4.11% and remarkable recovery strain rate of 98.1% in the second cycle, and a maximum 7.8% recovery strain and good recovery strain rate of 82.4% in the fifth cycle. In contrast, the sintered Ti-24Nb alloy exhibits recoverable strain of 4.58%, a recovery strain rate of 96.6% in the third cycle, and only 48.8% recovery strain rate in the fifth cycle. The transmission electron microscopy results indicate that the formation of microcracks and dislocations during the cycle compression results in significant recovery strain reduction for the Ti-24Nb alloy. The results provide guidelines to design high-performance Ti-24Nb-based alloys with excellent shape memory properties for structural applications.
•Our results provide guidelines to design high-performance Ti-24Nb-based alloys.•The Zr addition is effective to enhance strength and ductility of Ti-24Nb-based alloys.•The formation of microcracks and dislocations result in poor cycle stability of superelasticity.
Abstract
Here we present a detailed study of the broadband noise in the power density spectra of the black hole X-ray binary MAXI J1820+070 during the hard state of its 2018 outburst, using Hard ...X-ray Modulation Telescope observations. The broadband noise shows two main humps, which might separately correspond to variability from a variable disk and two Comptonization regions. We fitted the two humps with multiple Lorentzian functions and studied the energy-dependent properties of each component up to 90–150 keV and their evolution with spectral changes. The lowest-frequency component is considered as the subharmonic of the quasiperiodic oscillation component and shows a different energy dependence compared with other broadband noise components. We found that although the fractional rms of all the broadband noise components mainly decreases with the energy, their rms spectra are different in shape. Above ∼20–30 keV, the characteristic frequencies of these components increase sharply with the energy, meaning that the high-energy component is more variable on short timescales. Our results suggest that the hot inner flow in MAXI J1820+070 is likely to be inhomogeneous. We propose a geometry with a truncated accretion disk and two Comptonization regions.
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