A
bstract
Using (448
.
1
±
2
.
9)
×
10
6
ψ
(3686) events collected with the BESIII detector at the BEPCII collider, the decay
ψ
(3686)
→
Σ
−
Σ
¯
+
is observed for the first time with a branching ...fraction of (2
.
82
±
0
.
04
stat
.
±
0
.
08
syst
.
)
×
10
−
4
, and the angular parameter
α
Σ
−
is measured to be 0
.
96
±
0
.
09
stat
.
±
0
.
03
syst
.
.
The aluminide coating was prepared on Ti-6Al-2Zr-1Mo-1 V titanium alloy by pack cementation to enhance the high temperature oxidation resistance for aircraft and aerospace applications. High ...temperature oxidation behaviors of packing cementation coated and uncoated titanium alloy samples were comparatively investigated by isothermal oxidation at 800 °C and 900 °C in air. The results show that the compact coating with about 60 μm thick was composed of TiAl3. With isothermal oxidation for 100 h at 800 and 900 °C, the weight gains of the coated samples are 1.29 mg·cm−2 and 4.06 mg·cm−2 respectively, which are about 2/5 and 1/5 of that of titanium alloy substrates (3.20 mg·cm−2 and 20.33 mg·cm−2). The excellent oxidation resistance performance is attributed to the formation of a continuous and dense Al2O3 layer on the TiAl3 coating surface, which was effective to prevent the O element diffusing into the coating and then reduce the oxidation rate.
•Aluminide coating was prepared on Ti-6Al-2Zr-1Mo-1 V alloy by pack cementation.•The coating used NH4Cl as activator and CeO2 as accelerant.•The coating improved oxidation resistance of titanium alloy at 800 and 900 °C.
The phase evolution and magnetic properties of FeCoNiSi high-entropy alloy prepared by high-pressure solidification were investigated. The results showed that the Ni-rich second phases (SPs), ...dispersed in the FeCoNiSi alloy matrix during the initial application of 0.1 MPa solidification pressure, aggregated as the pressure was further increased. In addition, we observed an increase in saturation magnetization <inline-formula> <tex-math notation="LaTeX">M_{s} </tex-math></inline-formula> (from 77 to 86 emu/g) and a decrease in the intrinsic coercivity <inline-formula> <tex-math notation="LaTeX">H_{\mathbf {MC}} </tex-math></inline-formula> (from 75 to 49 Oe) when the alloy solidification pressure increased from 0.1 MPa to 7 GPa. Based on the micromagnetic calculations, the dispersed SPs separate the continuous magnetic moment in the matrix and delay the magnetization process. The reversed domain is prone to nucleate at the interface of the SPs and matrix due to its low domain wall energy and demagnetization energy during magnetization. Therefore, the dispersed SPs demonstrate a pinning effect on magnetic domains in the matrix compared with aggregated SPs.
A
bstract
Using a sample of (10
.
09
±
0
.
04)
×
10
9
J/ψ
decays collected with the BESIII detector, partial wave analyses of the decay
J
/
ψ
→
γ
K
S
0
K
S
0
π
0
are performed within the
K
S
0
K
S
0
...π
0
invariant mass region below 1.6 GeV/
c
2
. The covariant tensor amplitude method is used in both mass independent and mass dependent approaches. Both analysis approaches exhibit dominant pseudoscalar and axial vector components, and show good consistency for the other individual components. Furthermore, the mass dependent analysis reveals that the
K
S
0
K
S
0
π
0
invariant mass spectrum for the pseudoscalar component can be well described with two isoscalar resonant states using relativistic Breit-Wigner model, i.e., the
η
(1405) with a mass of
1391.7
±
0.7
−
0.3
+
11.3
MeV/
c
2
and a width of
60.8
±
1.2
−
12.0
+
5.5
MeV, and the
η
(1475) with a mass of
1507.6
±
1.6
−
32.2
+
15.5
MeV/
c
2
and a width of
115.8
±
2.4
−
10.9
+
14.8
MeV. The first and second uncertainties are statistical and systematic, respectively. Alternate models for the pseudoscalar component are also tested, but the description of the
K
S
0
K
S
0
π
0
invariant mass spectrum deteriorates significantly.
Y-doped V
2
O
5
was prepared by the sol-gel method combined with the freeze drying technique followed by annealing in air. The microstructure of the Y-doped V
2
O
5
was analyzed by XRD, SEM, XPS, and ...first-principles calculations. The electrochemical performance of the Y-doped V
2
O
5
was characterized by CV, EIS, and charge-discharge tests. The results demonstrated that Y doping had great influence on the morphology and crystalline orientation of the prepared V
2
O
5
sample. In particular, Y formed covalent bonds with the adjacent O atoms within the V
2
O
5
layers and decreased the bond orders of the neighboring V-O bonds. Compared with undoped V
2
O
5
, Y-doped V
2
O
5
showed much improved rate capability, higher lithium ion diffusion coefficient, lower electrochemical reaction resistance, and greatly enhanced cycling stability. Y-doped V
2
O
5
could be a promising cathode material for lithium ion batteries.
Y-doped V
2
O
5
shows greatly enhanced cycling stability, better rate capability, and a higher Li
+
diffusion coefficient than the pure V
2
O
5
counterpart.
Display omitted
The industrial applications of Mg and its alloys are restricted by their poor corrosion resistances, owing to the rapid dissolution and hydrogen evolution behaviors. In this study, a ...sequentially bridged reduced graphene oxide (RGO)/bistriethoxysilylethane (BTSE) coating is successfully grafted on the surface of Mg alloy substrate, to simultaneously inhibit the corrosion and wear behaviors. It exhibits well-aligned biomimetic nacre-like “bricks and mortar” structure connected by covalent bonding networks, consisting of the Si-O-C bonds between the RGO sheets and the Si-O-Si bonds derived from BTSE self-crosslinking reactions. The reduced porosity and defects lead to a high continuity and integrity of the RGO/BTSE coating, which decreases the corrosion rate by an order of magnitude compared with bare Mg substrate and RGO coated sample, owing to the enhanced barrier effect and weakened galvanic corrosion. In addition, the hybrid coating also performs well anti-wear property due to the intrinsic lubrication of RGO sheets, which can protect the substrate from friction and wear. The wear rate decreases from 3.5 × 10−3 mm3N-1 m-1 of bare Mg alloy to 5.13 × 10-5 mm3N-1 m-1 of RGO/BTSE coated sample. The interlayer slipping between the RGO sheets effectively decreases friction resistance, although the incorporation of BTSE slightly increases their shear resistance.
A
bstract
Using data samples with an integrated luminosity of 19 fb
−
1
at twenty-eight center-of-mass energies from 3.872 GeV to 4.700 GeV collected with the BESIII detector at the BEPCII ...electron-positron collider, the process
e
+
e
−
→
ηπ
+
π
−
and the intermediate process
e
+
e
−
→
ηρ
0
are studied for the first time. The Born cross sections are measured. No significant resonance structure is observed in the cross section lineshape.
The decay
D
→
K
-
π
+
is studied in a sample of quantum-correlated
D
D
¯
pairs, based on a data set corresponding to an integrated luminosity of 2.93 fb
-
1
collected at the
ψ
(
3770
)
resonance by ...the BESIII experiment. The asymmetry between
C
P
-odd and
C
P
-even eigenstate decays into
K
-
π
+
is determined to be
A
K
π
=
0.132
±
0.011
±
0.007
, where the first uncertainty is statistical and the second is systematic. This measurement is an update of an earlier study exploiting additional tagging modes, including several decay modes involving a
K
L
0
meson. The branching fractions of the
K
L
0
modes are determined as input to the analysis in a manner that is independent of any strong phase uncertainty. Using the predominantly
C
P
-even tag
D
→
π
+
π
-
π
0
and the ensemble of
C
P
-odd eigenstate tags, the observable
A
K
π
π
π
π
0
is measured to be
0.130
±
0.012
±
0.008
. The two asymmetries are sensitive to
r
D
K
π
cos
δ
D
K
π
, where
r
D
K
π
and
δ
D
K
π
are the ratio of amplitudes and phase difference, respectively, between the doubly Cabibbo-suppressed and Cabibbo-favoured decays. In addition, events containing
D
→
K
-
π
+
tagged by
D
→
K
S
,
L
0
π
+
π
-
are studied in bins of phase space of the three-body decays. This analysis has sensitivity to both
r
D
K
π
cos
δ
D
K
π
and
r
D
K
π
sin
δ
D
K
π
. A fit to
A
K
π
,
A
K
π
π
π
π
0
and the phase-space distribution of the
D
→
K
S
,
L
0
π
+
π
-
tags yields
δ
D
K
π
=
187.6
-
9.7
+
8.9
-
6.4
+
5.4
∘
, where external constraints are applied for
r
D
K
π
and other relevant parameters. This is the most precise measurement of
δ
D
K
π
in quantum-correlated
D
D
¯
decays.
A
bstract
The Born cross sections of the
e
+
e
−
→ D
*+
D
*
−
and
e
+
e
−
→ D
*+
D
−
processes are measured using
e
+
e
−
collision data collected with the BESIII experiment at center-of-mass ...energies from 4.085 to 4.600 GeV, corresponding to an integrated luminosity of 15
.
7 fb
−
1
. The results are consistent with and more precise than the previous measurements by the Belle, Babar and CLEO collaborations. The measurements are essential for understanding the nature of vector charmonium and charmonium-like states.
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