Abstract
V606 Centauri (V606 Cen) is an early B-type close binary with an orbital period of 1.4950935 days, and its complete light curves are very difficult to observe on the ground. By analyzing the ...continuous light curve obtained by TESS, we found that it is a marginal contact binary with a very low fill-out factor of about 2%. The
O
−
C
diagram of V606 Cen is constructed for the first time based on 118.8 yr of eclipse times. The
O
−
C
diagram has been found to show a downward parabolic change together with a cyclic oscillation with a semiamplitude of 0.0545 days and a period of 88.3 yr. The downward parabolic variation reveals a linear period decrease at a rate of
dP
/
dt
= −2.08 × 10
−7
days yr
−1
that can be explained by the mass transfer from the more massive component to the less massive one. Both the marginal contact configuration and the continuous period decrease suggest that V606 Cen is a newly formed contact binary via Case A mass transfer. The cyclic change in the
O
−
C
diagram can be explained by the light-travel time effect via the presence of a third body. The lowest mass of the tertiary companion is determined to be
M
3
= 4.51 (±0.43)
M
⊙
and the tertiary is orbiting around the central eclipsing binary in a nearly circular orbit (
e
= 0.33). All of the results indicate that V606 Cen is a newly formed massive contact binary in a hierarchical triple system.
Background
Enucleation of pancreatic neuroendocrine tumours (pNETs) via robotic surgery has rarely been described. This study sought to assess the safety and efficiency of robotic surgery for the ...enucleation of small pNETs.
Methods
A comparison was conducted of enucleation of pNETs smaller than 2 cm by robotic or open surgery between January 2000 and May 2015. Propensity score matching was used to balance sex, age, BMI, tumour location and tumour diameter. Pathological results, safety‐related outcomes (postoperative pancreatic fistula (POPF) rate, estimated blood loss, and short‐term mortality and morbidity) and efficiency‐related outcomes (duration of surgery and postoperative length of hospital stay) were compared between the groups.
Results
A cohort of 120 patients with pNET were enrolled in the study (1 : 1 matched for open or robotic surgery, 60 per group). Ninety‐three patients (77·5 per cent) had a grade 1 tumour and 114 (95·0 per cent) had an insulinoma. Robotic surgery had a conversion rate of 5 per cent (3 of 60), and was not associated with an increased POPF rate (10 per cent versus 17 per cent after open surgery; P = 0·283) or grade III–V surgical complications according to the Dindo–Clavien classification (3 versus 10 per cent respectively; P = 0·272). Estimated blood loss was reduced with the robotic approach (32·5 versus 80·0 ml in the open group; P = 0·008), as was duration of surgery (117 versus 150 min; P < 0·001). Length of hospital stay after surgery was similar in the two groups (12·0 versus 13·5 days respectively; P = 0·071).
Conclusion
Robotic surgery for enucleation of pNETs smaller than 2 cm did not increase POPF or major complication rates, and reduced the duration of surgery and estimated blood loss, compared with open surgery. Registration number: NCT02125929 (
https://www.clinicaltrials.gov/).
Robot beats surgeon
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Particles directly produced at electron–positron colliders, such as the J/ψ meson, decay with relatively high probability into a baryon–antibaryon pair1. For spin-1/2 baryons, the pair can have the ...same or opposite helicites. A non-vanishing phase ΔΦ between the transition amplitudes to these helicity states results in a transverse polarization of the baryons2–4. From the joint angular distribution of the decay products of the baryons, this phase as well as the parameters characterizing the baryon and the antibaryon decays can be determined. Here, we report the measurement of ΔΦ = 42.4 ± 0.6 ± 0.5° using Λ → pπ− and Λ¯→p¯π+,n¯π0 decays at BESIII. We find a value for the Λ → pπ− decay parameter of α− = 0.750 ± 0.009 ± 0.004, 17 ± 3% higher than the current world average, which has been used as input for all Λ polarization measurements since 19785,6. For Λ¯→p¯π+ we find α+ = −0.758 ± 0.010 ± 0.007, giving ACP = (α− + α+)/(α− − α+) = −0.006 ± 0.012 ± 0.007, a precise direct test of charge–parity symmetry (CP) violation in Λ decays.The decay asymmetry and helicity phase of polarized baryon–antibaryon pairs are measured at the BESIII experiment, testing charge–parity symmetry and revealing a discrepancy of the Λ → pπ− decay asymmetry with respect to the current world average.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
Semidetached binaries provide a valuable test of the evolutionary models of interacting binaries where the mass is transferring from one component to the other, and the evolutions of both ...components will be changed. Many results of semidetached binaries have been obtained in the Milky Way, while there are few studies in the Andromeda galaxy (M31). By analyzing the light curves of 12 eclipsing binaries observed by Vilardell et al., we determined the fundamental parameters of these systems using the Wilson and Devinney method. It is discovered that they are semidetached binaries where the less massive components have filled their Roche lobes, while the more massive ones are detached from the lobes. We calculated their times of light minimum for the first time. The primary stars in those semidetached binaries have different mass ratios and fill-out factors and they are good sources to investigate the binary evolution in M31. It is found that the mass ratio is correlated with the fill-out factor of the primary. Systems with higher mass ratios tend to have lower fill-out factors. These results can be explained that the mass transfer from the less massive component to the more massive one. Moreover, the photometric solutions reveal that the secondary components are more evolved than the primary ones indicating that they are formed from originally detached binary systems via a case A mass transfer. These binaries have experienced the mass-reverse evolution and are at the late stage of a case A evolution in the nearby galaxy M31.
We demonstrate spin-orbit torque (SOT) switching of amorphous CoTb single-layer films with perpendicular magnetic anisotropy (PMA). The switching sustains even the film thickness is above 10 nm, ...where the critical switching current density stays almost constant. Without the need of overcoming the strong interfacial Dzyaloshinskii-Moriya interaction caused by the heavy metal, a quite low assistant field of ∼20 Oe is sufficient to realize the full switching. The SOT effective field decreases and undergoes a sign change with the decrease of the Tb concentration, implying that a combination of the spin Hall effect from both Co and Tb as well as an asymmetric spin current absorption accounts for the SOT switching mechanism. Our findings advance the use of magnetic materials with bulk PMA for energy-efficient and thermally stable nonvolatile memories, and add a different dimension for understanding the ordering and asymmetry in amorphous thin films.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
To balance the utilization of rare earth (RE) resource and develop Ce-based permanent magnets with high performance/cost ratio, the role of La substitution in the melt-spun (Ce
1−
x
La
x
)
y
Fe
14
B ...(
x
= 0–0.4, and 0.5;
y
= 2–4) alloys has been investigated. It has been confirmed that the hard magnetic properties of Ce-based magnets can be effectively enhanced by partial substitution of La. The maximum (
BH
)
max
of (Ce,La)–Fe–B alloys can be obtained at a Ce:La atomic ratio of 7:3. The lattice parameters and Curie temperature of the hard magnetic (Ce/La)
2
Fe
14
B phase increase linearly with increasing La content. Three different alloy systems with
y
= 2, 2.5 and 3 show similar behavior of magnetic properties dependences on La. In the RE-rich compositions, La substitution for Ce can effectively inhibit the precipitation of the CeFe
2
phase. A solid solution, Ce(La) phase with a space group of Fm-3m, appears in the (Ce
0.7
La
0.3
)
y
Fe
14
B alloys with
y
≥ 3.5. A good combination of magnetic properties with
H
cj
= 345 kA/m,
J
5T
= 1.03 T,
J
r
= 0.60 T, and (
BH
)
max
= 6.3 MGOe is obtained in (Ce
0.7
La
0.3
)
2.5
Fe
14
B alloy. In addition, 30 at.% La substitution for Ce can significantly refine the grains, resulting in the enhancement of exchange coupling interaction. The present finding is beneficial for designing new and low-cost magnetic materials.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•La-Al-Cu alloys were employed for grain boundary diffusion for the first time.•Coercivity and thermal stability of NdFeB magnet are enhanced by La-Al-Cu diffusion.•Optimized microstructure after ...grain boundary diffusion is observed and confirmed.•Diffusion behavior and diffusion coefficients of La, Al and Cu are investigated.
Different from many previous reports, La-Al-Cu alloys with different Al/Cu ratios containing only high abundant rare earth element La were employed for grain boundary diffusion treatment for sintered NdFeB permanent magnets. It is found that Al and Cu contents should be optimized to achieve coercivity enhancement. The coercivity of the magnet was enhanced from 1000 to 1006, 1077 and 1156 kA/m after La70Al10Cu20, La70Al15Cu15 and La70Al20Cu10 alloys diffusion, at 800 °C for 1 h followed by 500 °C for 3 h. The coercivity stability was also improved, indicated by the enhanced temperature coefficient of β from −0.63 to −0.61, −0.61 and −0.60%/K. Microstructure investigation indicates that the formation of continuous grain boundary phase after diffusion reduces the magnetic exchange interaction and contributes to the enhanced coercivity. After diffusion, the La2O3 phase was observed in both the triple junction and strip grain boundary. La, Al and Cu elements showed different distributions in the magnets. The diffusion coefficients obtained from Fick’s second law indicate that La diffuses faster than Al and Cu at 800 °C, which explains the various effects of the diffusion sources and different coercivity enhancements by the alloys with different Al/Cu ratios. Although the process should be further optimized, the current results demonstrate that the grain boundary diffusion using low cost La-Al-Cu alloys can improve the microstructure and enhance the coercivity of NdFeB magnets.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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.
To release the pressure on the supply of critical rare earths (REs), much effort has been made to substitute Nd and Pr by more highly abundant La, Ce, and Y elements in Nd-Fe-B magnets. The chemical ...heterogeneity reported in multi-main-phase sintered magnets is a promising solution to suppress the magnetic dilution of La-, Ce-, or Y-added Nd-Fe-B magnets. Here, we investigated the nanocrystalline (Ce
1−
x
Y
x
)
17
Fe
75
Si
3
B
6
(
x
= 0-0.6) alloys prepared by melt spinning and observed an unusual chemical heterogeneity in the (Ce
0.5
Y
0.5
)
17
Fe
75
Si
3
B
6
alloy. Here, the Y segregation in RE
2
Fe
14
B (2 : 14 : 1) phase and Ce segregation in REFe
2
(1 : 2) phase were demonstrated due to the significantly different Ce and Y diffusion rates in these two phases. As a result, an extremely high coercivity
H
c
of 432 kA m
−1
and a greatly enhanced maximum energy product (
BH
)
max
of 7.1 MGOe with Curie temperature
T
c
of 547 K were obtained. In the alloys with
x
= 0.1-0.4,
H
c
decreased with Y substitution but the remanence
J
r
, (
BH
)
max
and
T
c
did not increase significantly despite the higher magnetization
M
s
and
T
c
of the Y
2
Fe
14
B phase than those of Ce
2
Fe
14
B. The reason for this could be attributed to the formation of a large amount of 1 : 2 phase and the insignificant Y and Ce segregations. For the alloy with
x
= 0.6, though a further increase of
J
r
was obtained, (
BH
)
max
value of 7.2 MGOe was similar to that of the alloy with
x
= 0.5 because
H
c
was significantly reduced. The unique microstructural evolution was responsible for the notable change in magnetic properties. The nano-level chemical heterogeneity manifested by the present work offers a potential approach to improve the cost performance and understand the physical mechanism of free-RE magnets.
The nano-level chemical heterogeneity due to the Y segregation in RE
2
Fe
14
B phase and Ce segregation in REFe
2
phase enhance the hard magnetic properties of (Y,Ce)-Fe-B alloys, which offers a potential approach to improve the cost performance of free-RE magnets.
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