Abstract
Recent discoveries of double neutron star (DNS) mergers and ultra-stripped supernovae (SNe) raise the questions of their origin and connection. We present the first 1D model of a DNS ...progenitor system that is calculated self-consistently until an ultra-stripped iron core collapse. We apply the
MESA
code starting from a post-common-envelope binary consisting of a 1.35
M
⊙
NS and a 3.20
M
⊙
zero-age main-sequence helium star and continue the modeling via Case BB Roche-lobe overflow until the infall velocity of the collapsing iron core exceeds 1000 km s
−1
. The exploding star has a total mass of ∼1.90
M
⊙
, consisting of a ∼0.29
M
⊙
He-rich envelope embedding a CO core of ∼1.61
M
⊙
and an iron-rich core of ∼1.50
M
⊙
. The resulting second-born NS has an estimated mass of ∼1.44
M
⊙
, and we discuss the fate of the post-SN system, as well as the mild recycling of the first-born NS. Depending on the initial conditions, this family of systems is anticipated to reproduce the DNS mergers detected by the LIGO network.
Recent timing analysis reveals that the orbital period of the first-discovered accreting millisecond pulsar SAX J1808.4-3658 is increasing at a rate P sub( orb) = (3.89 plus or minus 0.15) x 10 ...super( -12) s s super( -1), which is at least one order of magnitude higher than the value arising from the conservative mass transfer. An ejection of mass-loss rate of 10 super( - 9) M... yr super( - 1) from the donor star at the inner Lagrangian point during the quiescence state could interpret the observed orbital-period derivative. However, it is unknown whether this source can offer such a high mass-loss rate. In this work, we attempt to investigate an evolutionary channel towards SAX J1808.4-3658. Once the accretion disc becomes thermally and viscously unstable, the spin-down luminosity of the millisecond pulsar and the X-ray luminosity during outbursts are assumed to evaporate the donor star, and the resulting winds carry away the specific orbital angular momentum at the inner Lagrangian point. Our scenario could yield the observed orbital period, the orbital-period derivative, and the peak X-ray luminosity during outbursts. Low-mass X-ray binaries with a 1.0 M... donor star, and an orbital period in the range of 0.8-1.5 d, may be the progenitor of SAX J1808.4-3658. Our numerical calculations propose that the current donor-star mass is 0.044 M..., which is approximately in agreement with the minimum mass of the donor star. In addition, our scenario can also account for the formation of black widows or the diamond planets like PSR J1719-1438. (ProQuest: ... denotes formulae/symbols omitted.)
Abstract Recently, ultraluminous X-ray source (ULX) M82 X-2 has been identified to be an accreting neutron star, which has a P = 1.37 s spin period, and is spinning up at a rate $\dot{P}=-2.0\times ...10^{-10}\,\rm s\,s^{-1}$. Interestingly, its isotropic X-ray luminosity Liso = 1.8 × 1040 erg s− 1 during outbursts is 100 times the Eddington limit for a 1.4 M⊙ neutron star. In this Letter, based on the standard accretion model we attempt to constrain the dipolar magnetic field of the pulsar in ULX M82 X-2. Our calculations indicate that the accretion rate at the magnetospheric radius must be super-Eddington during outbursts. To support such a super-Eddington accretion, a relatively high multipole field ( ≳ 1013 G) near the surface of the accretor is invoked to produce an accreting gas column. However, our constraint shows that the surface dipolar magnetic field of the pulsar should be in the range of 1.0−3.5 × 1012 G. Therefore, our model supports that the neutron star in ULX M82 X-2 could be a low-magnetic-field magnetar (proposed by Tong) with a normal dipolar field (∼1012 G) and relatively strong multipole field. For the large luminosity variations of this source, our scenario can also present a self-consistency interpretation.
Photoresponsive polymers can be conveniently used to fabricate anti‐counterfeiting materials through photopatterning. However, an unsolved problem is that ambient light and heat can damage ...anti‐counterfeiting patterns on photoresponsive polymers. Herein, photo‐ and thermostable anti‐counterfeiting materials are developed by photopatterning and thermal annealing of a photoresponsive conjugated polymer (MC‐Azo). MC‐Azo contains alternating azobenzene and fluorene units in the polymer backbone. To prepare an anti‐counterfeiting material, an MC‐Azo film is irradiated with polarized blue light through a photomask, and then thermally annealed under the pressure of a photonic stamp. This strategy generates a highly secure anti‐counterfeiting material with dual patterns, which is stable to sunlight and heat over 200 °C. A key for the stability is that thermal annealing promotes interchain stacking, which converts photoresponsive MC‐Azo to a photostable material. Another key for the stability is that the conjugated structure endows MC‐Azo with desirable thermal properties. This study shows that the design of photopatternable conjugated polymers with thermal‐annealing‐promoted interchain stacking provides a new strategy for the development of highly stable and secure anti‐counterfeiting materials.
Photo‐ and thermostable anti‐counterfeiting materials are designed using a photopatternable conjugated polymer with thermal‐annealing‐promoted interchain stacking. To prepare anti‐counterfeiting materials, the polymer is irradiated with polarized light through a photomask, and thermally annealed under a photonic stamp. This strategy generates a highly secure anti‐counterfeiting material with dual patterns, which is stable to sunlight and heat over 200 °C.
Abstract
Black hole (BH) ultracompact X-ray binaries (UCXBs) are potential Galactic low-frequency gravitational wave (GW) sources. As an alternative channel, BH UCXBs can evolve from BH+He star ...binaries. In this work, we perform a detailed stellar evolution model for the formation and evolution of BH UCXBs evolving from the He star channel to diagnose their detectability as low-frequency GW sources. Our calculations found that some nascent BH+He star binaries after the common-envelope (CE) phase could evolve into UCXB-LISA sources with a maximum GW frequency of ∼5 mHz, which can be detected in a distance of 10 kpc (or 100 kpc). Once BH+He star systems become UCXBs through mass transfer, they would emit X-ray luminosities of ∼10
38
erg s
−1
, making them ideal multimessenger objects. If the initial He-star masses are ≥0.7
M
⊙
, those systems are likely to experience two Roche lobe overflows, and the X-ray luminosity can reach a maximum of 3.5 × 10
39
erg s
−1
in the second mass-transfer stage. The initial He-star masses and initial orbital periods of progenitors of Galactic BH UCXB-LISA sources are in the range of 0.32–2.9
M
⊙
and 0.02–0.19 days, respectively. Nearly all BH+He star binaries in the above parameter space can evolve into GW sources whose chirp masses can be accurately measured. Employing a population synthesis simulation, we predict the birthrate and detection number of Galactic BH UCXB-LISA sources evolving from the He star channel are
R
= 2.2 × 10
−6
yr
−1
and 33 for an optimistic CE parameter, respectively.
Abstract
Recent discoveries of gravitational wave (GW) events most likely originating from black hole (BH) + neutron star (NS) mergers reveal the existence of BH+NS binaries. The formation of BH+NS ...binaries and their merger rates through isolated binary evolution have been investigated extensively with population synthesis simulations. A detailed stellar evolution modeling of the formation of this population, however, is missing from the literature. In this work, we create the first complete 1D model of more than 30 BH+NS progenitor systems, which are calculated self-consistently until collapse of the iron core with infall velocity exceeding 1000 km s
−1
. Focusing on the progenitors of BH–NS GW sources, we apply the
MESA
code starting from a post-common-envelope binary with short orbital period (<1 day) consisting of a BH and a zero-age main-sequence helium star that experiences stable mass transfer. The (ultra)stripped supernova explosion is subsequently modeled using a semianalytic method to reveal final remnant masses and momentum kicks. Three example systems (A, B, and C) eventually evolve into BH+NS binaries with component masses of (
M
BH
,
M
NS
) = (8.80, 1.53), (8.92, 1.45), and (5.71, 1.34)
M
⊙
, respectively. These NS masses could be significantly larger depending on the exact mass cut during the supernova explosion. These BH+NS systems are likely to merge and produce GW events within a Hubble time. System C is a potential progenitor of a GW200115-like event, while Systems A and B are possible candidates for a GW200105-like event and may represent the final destiny of the X-ray binary SS 433.
Abstract
Recently, repeating fast radio bursts (FRBs) with a period of PFRB = 16.35 ± 0.18 d from FRB 180916.J0158+65 were reported. It still remains controversial how such a periodicity might arise ...for this FRB. In this Letter, based on an assumption of a young pulsar surrounding by a debris disk, we attempt to diagnose whether Lense–Thirring precession of the disk on the emitter can produce the observed periodicity. Our calculations indicate that the Lense–Thirring effect of a tilted disk can result in a precession period of 16 d for a mass inflow rate of 0.5–1.5 × 1018 g s−1, a pulsar spin period of 1–20 ms, and an extremely low viscous parameter α = 10−8 in the disk. The disk mass and the magnetic field of the pulsar are also constrained to be ∼10−3 M⊙ and <2.5 × 1013 G. In our model, a new-born pulsar with normal magnetic field and millisecond period would successively experience the accretion and propeller phases, and is visible as a strong radio source in the current stage. The rotational energy of such a young neutron star can provide the observed radio bursting luminosity for 400 yr.
Objectives
Based on previous reports that ginsenosides have been shown to exert better preventive effects on cisplatin‐induced kidney injury, the present work aims to evaluate the protective effects ...of ginsenoside Rb3 (G‐Rb3) on cisplatin‐induced renal damage and underlying mechanisms in vivo and in vitro.
Materials and methods
The protective effect of G‐Rb3 on cisplatin‐induced acute renal failure in ICR mouse model and HEK293 cell model was investigated, and the underlying possible mechanisms were also explored. For animal experiment, renal function, kidney histology, inflammation, oxidative stress, relative protein molecules involved in apoptosis and autophagy signalling pathways were assessed. In addition, rapamycin (a specific inhibitor of mTOR), compound C (a specific inhibitor of AMPK) and acetylcysteine (NAC, a specific ROS scavenger) were employed to testify the effects of AMPK/mTOR signal pathway on the protective effects of G‐Rb3 in HEK293 cells.
Results
Pre‐treatment with G‐Rb3 at doses of 10 and 20 mg/kg for ten days significantly reversed the increases in serum creatinine (CRE), blood urea nitrogen (BUN) and malondialdehyde (MDA), and decrease in glutathione (GSH) content and superoxide dismutase (SOD) activity. Histopathological examination further revealed that G‐Rb3 inhibited cisplatin‐induced nephrotoxicity. G‐Rb3 diminished cisplatin‐induced increase in protein expression levels of p62, Atg3, Atg5 and Atg7, and decrease in protein expression level of p‐mTOR and the ratio of LC3‐I/LC3‐II, indicating that G‐Rb3 suppressed cisplatin‐induced activation of autophagy. Inhibition of autophagy induced inactivation of apoptosis, which suggested that autophagy played an adverse effect on cisplatin‐evoked renal damage. Further, we found that G‐Rb3 might potentially modulate the expressions of AMPK‐related signal pathways.
Conclusions
These findings clearly suggested that G‐Rb3‐mediated alleviation of cisplatin‐induced nephrotoxicity was in part due to regulation of AMPK‐/mTOR‐mediated autophagy and inhibition of apoptosis in vitro and in vivo.
Sco X-1 is the brightest persistent X-ray source in the sky. It is generally believed that Sco X-1 is a low-mass X-ray binary containing a neutron star that accretes from a low-mass donor star where ...the mass transfer is driven by magnetic braking. However, the mass transfer rate predicted by the standard magnetic braking model is at least one order of magnitude lower than the rate inferred by X-ray luminosity. In this work, we investigate whether this source could have evolved from an intermediate-mass X-ray binary including Ap/Bp stars with a slightly strong magnetic field of 300–1000 G. The coupling between the magnetic field and an irradiation-driven wind induced by the X-ray flux from the accretor can yield strong magnetic braking that could give rise to a relatively high mass transfer rate. According to the observed orbital period, the mass transfer rate, the mass ratio, and the donor star spectral type, the progenitor of Sco X-1 should be an intermediate-mass X-ray binary including a 1.6−1.8 M⊙ Ap/Bp donor star in a 1.3−1.5 day orbit. We therefore propose that anomalous magnetic braking of Ap/Bp stars provides an alternative evolutionary channel to some of the luminous X-ray sources.
Background
Intrahepatic cholangiocarcinoma (ICC) is the second most common tumor in primary liver cancer, but the prognostic factors associated with long-term outcomes after surgical resection remain ...poorly defined. This study aimed to develop a novel prognostic classifier for patients with ICC after surgery.
Methods
Using a proteomics approach, we screened tumor markers that up-regulated in ICC tissues, and narrowed down by bioinformatics analysis, western blot and immunohistochemistry. Prognostic markers were identified using Cox regression analyses in primary training cohort and the predictive models for time to recurrence (TTR) were established. The predictive accuracy of predictive model was validated in external validation cohort and prospective validation cohort. MTT assay, clonal formation assay and trans-well assays were used to verify the effect on the proliferation and migration in ICC cell line.
Results
Triosephosphate isomerise (TPI1) was significantly up-regulated in ICC tissues and Kaplan–Meier analysis reveals that higher TPI1 expression was strongly correlated with higher recurrence rate of ICC patients. In the primary training cohort, mean TTR was significantly longer (
p
< 0.0001) than in the low-risk group (26.9 months for TTR, 95% CI 22.4–31.5) than in the high-risk group (14.5 months for TTR, 95% CI 10.6–18.4). Similar results were observed in two validation cohorts. In addition, a nomogram to predict recurrence was developed. Moreover, Knockdown of TPI1 by shRNA inhibited ICC cell growth, colony information, migration, invasion in vitro.
Conclusions
Current prognostic models were accurate in predicting recurrence for ICC patients after surgical resection.
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