We measure the Born cross sections of the process e+e−→K+K−K+K− at center-of-mass (c.m.) energies, s, between 2.100 and 3.080 GeV. The data were collected using the BESIII detector at the BEPCII ...collider. An enhancement at s=2.232 GeV is observed, very close to the e+e−→ΛΛ¯ production threshold. A similar enhancement at the same c.m. energy is observed in the e+e−→ϕK+K− cross section. The energy dependence of the K+K−K+K− and ϕK+K− cross sections differs significantly from that of e+e−→ϕπ+π−.
We search for J / ψ radiative decays into a weakly interacting neutral particle, namely an invisible particle, using the J / ψ produced through the process ψ ( 3686 ) → π + π − J / ψ in a data sample ...of ( 448.1 ± 2.9 ) × 10 6 ψ ( 3686 ) decays collected by the BESIII detector at BEPCII. No significant signal is observed. Using a modified frequentist method, upper limits on the branching fractions are set under different assumptions of invisible particle masses up to 1.2 GeV / c 2 . The upper limit corresponding to an invisible particle with zero mass is 7.0 × 10 −7 at the 90% confidence level.
Tea is the world's most popular non-alcoholic beverage. China and India are known to be the largest tea producing countries and recognized as the centers for the domestication of the tea plant ...(Camellia sinensis (L.) O. Kuntze). However, molecular studies on the origin, domestication and relationships of the main teas, China type, Assam type and Cambod type are lacking.
Twenty-three nuclear microsatellite markers were used to investigate the genetic diversity, relatedness, and domestication history of cultivated tea in both China and India. Based on a total of 392 samples, high levels of genetic diversity were observed for all tea types in both countries. The cultivars clustered into three distinct genetic groups (i.e. China tea, Chinese Assam tea and Indian Assam tea) based on STRUCTURE, PCoA and UPGMA analyses with significant pairwise genetic differentiation, corresponding well with their geographical distribution. A high proportion (30%) of the studied tea samples were shown to possess genetic admixtures of different tea types suggesting a hybrid origin for these samples, including the Cambod type.
We demonstrate that Chinese Assam tea is a distinct genetic lineage from Indian Assam tea, and that China tea sampled from India was likely introduced from China directly. Our results further indicate that China type tea, Chinese Assam type tea and Indian Assam type tea are likely the result of three independent domestication events from three separate regions across China and India. Our findings have important implications for the conservation of genetic stocks, as well as future breeding programs.
Metastasis is the chief cause of mortality from cancer, but the mechanisms leading to metastasis are poorly understood. We used a proteomics approach to screen for metastasis-associated proteins and ...found that collapsin response mediator protein-4 (CRMP4) expression was inversely associated with the lymph node metastasis of prostate cancer (PCa). Subsequent in vitro and in vivo studies revealed that overexpression of CRMP4 not only suppressed the invasion ability of PCa cells, but also strongly inhibited tumor metastasis in an animal model. Furthermore, methylation of a CpG island within the promoter region of the CRMP4 gene is responsible for downregulation of CRMP4 expression. Thus, in this study, we show new function of CRMP4 as a metastasis-suppressor in PCa. The findings provide new mechanistic insights into metastasis and therapeutic potential for this most common male cancer.
SARS-CoV-2 infection causes COVID-19. Several clinical reports have linked COVID-19 during pregnancy to negative birth outcomes and placentitis. However, the pathophysiological mechanisms ...underpinning SARS-CoV-2 infection during placentation and early pregnancy are not clear. Here, to shed light on this, we used induced trophoblast stem cells to generate an in vitro early placenta infection model. We identified that syncytiotrophoblasts could be infected through angiotensin-converting enzyme 2 (ACE2). Using a co-culture model of vertical transmission, we confirmed the ability of the virus to infect syncytiotrophoblasts through a previous endometrial cell infection. We further demonstrated transcriptional changes in infected syncytiotrophoblasts that led to impairment of cellular processes, reduced secretion of HCG hormone and morphological changes vital for syncytiotrophoblast function. Furthermore, different antibody strategies and antiviral drugs restore these impairments. In summary, we have established a scalable and tractable platform to study early placental cell types and highlighted its use in studying strategies to protect the placenta.
We report the discovery of two new unbound hypervelocity stars (HVSs) from the LAMOST spectroscopic surveys. They are, respectively, a B2V-type star of ∼7 M with a Galactic rest-frame radial velocity ...of 502 km s−1 at a Galactocentric radius of ∼21 kpc and a B7V-type star of ∼4 M with a Galactic rest-frame radial velocity of 408 km s−1 at a Galactocentric radius of ∼30 kpc. The origins of the two HVSs are not clear given their currently poorly measured proper motions. However, the future data releases of Gaia should provide proper motion measurements accurate enough to solve this problem. The ongoing LAMOST spectroscopic surveys are expected to yield more HVSs to form a statistical sample, providing vital constraints on understanding the nature of HVSs and their ejection mechanisms.
•Moving crack in 1D hexagonal piezoelectric quasicrystals is studied.•Full electroelastic field induced by a running crack is obtained.•Field intensity factor is independent of the crack ...speed.•Energy release rate is dependent on the crack speed.•Crack bifurcation is judged by the maximum energy release rate.
A Yoffe-type moving crack in one-dimensional hexagonal piezoelectric quasicrystals is considered. The Fourier transform technique is used to solve a moving crack problem under the action of antiplane shear and inplane electric field. Full elastic stresses of phonon and phason fields and electric fields are derived for a crack running with constant speed in the periodic plane. Obtained results show that the coupled elastic fields inside piezoelectric quasicrystals depend on the speed of crack propagation, and exhibit the usual square-root singularity at the moving crack tip. Electric field and phason stresses do not have singularity and electric displacement and phonon stresses have the inverse square-root singularity at the crack tip for a permeable crack. The field intensity factors and energy release rates are obtained in closed form. The crack velocity does not affect the field intensity factors, but alters the dynamic energy release rate. Bifurcation angle of a moving crack in a 1D hexagonal piezoelectric quasicrystal is evaluated from the viewpoint of energy balance. Obtained results are helpful to better understanding crack advance in piezoelectric quasicrystals.
Amorphization by mechanical deformation Li, B.Y.; Li, A.C.; Zhao, S. ...
Materials science & engineering. R, Reports : a review journal,
June 2022, 2022-06-00, 20220601, Volume:
149
Journal Article
Peer reviewed
Amorphization of crystalline structures is a ubiquitous phenomenon in metals, ceramics, and intermetallic compounds. Although the amorphous phase generally has a higher Gibbs free energy than its ...crystalline counterpart, there are many methods by which amorphization can be generated. The requirement to create an amorphous phase from a solid crystalline one is to increase its free energy above a critical level which enables this transition. In this review, our focus is on amorphization induced by mechanical deformation which can be imparted by a variety of means, prominent among which are tribological processes, severe plastic deformation, nanoindentation, shock compression, diamond anvil cell and ball milling/mechanical alloying. The deformation introduces defects into the structure, raising its free energy to the level that it exceeds the one of the amorphous phase, thus propitiating conditions for amorphization. Experimental observations of amorphization in metallic alloys, intermetallic compounds, ionically and covalently bonded materials are presented and discussed. There is also an observation of amorphization in a biological material: it is generated by impact deformation of hydroxyapatite in the mantis shrimp club. We also focus on the fundamental mechanisms of plastic deformation of amorphous materials; this is a closely linked process by which deformation continues, beyond amorphization, in the new phase. Observations and analyses of amorphization are complemented by computational simulations that predict the process of mechanically-induced amorphization and address the mechanisms of this transformation.
ABSTRACT
We studied the 2018 outburst of the black hole transient H 1743 − 322 with a series of Insight-HXMT, NICER, and NuSTAR observations, covering the 1–120 keV band. With our broad-band X-ray ...spectral modelling, we confirm that the source remained in the low/hard state throughout the month-long outburst, although it became marginally softer at peak flux. We detected Type-C quasi-periodic oscillations (QPOs) and followed the evolution of their properties. The QPO frequency increased from ∼0.1 to ∼0.4 Hz during the rising phase of the outburst and decreased again in the decline. Continuum X-ray flux, power-law photon index, QPO frequency, and QPO root-mean-square amplitude were positively correlated. The QPO amplitude was slightly higher in the soft X-ray band (typical values of 12–16 per cent, compared with 8–10 per cent in the hard band). Our spectral-timing results shed light on the initial rising phase in the low/hard state, which has rarely been monitored with such high cadence, time resolution, and broad-band coverage. Combining spectral and timing properties, we find that ‘failed’ (hard state only) and ‘successful’ outbursts follow the same initial evolutionary track, although the former class of outburst never reaches the threshold for a transition to softer (thermally dominated) accretion regimes.
A
bstract
Based on
e
+
e
−
collision data collected at center-of-mass energies from 2.000 to 3.080 GeV by the BESIII detector at the BEPCII collider, a partial wave analysis is performed for the ...process
e
+
e
−
→
K
S
0
K
L
0
π
0
. The results allow the Born cross sections of the process
e
+
e
−
→
K
S
0
K
L
0
π
0
, as well as its subprocesses
e
+
e
−
→
K
∗
(892)
0
K
¯
0
and
K
2
∗
(1430)
0
K
¯
0
to be measured. The Born cross sections for
e
+
e
−
→
K
S
0
K
L
0
π
0
are consistent with previous measurements by BaBar, but with substantially improved precision. The Born cross section lineshape of the process
e
+
e
−
K
∗
(892)
0
K
¯
0
is consistent with a vector meson state around 2.2 GeV with a significance of 3.2
σ
. A Breit-Wigner fit determines its mass as
M
Y
= (2164
.
7
±
9
.
1
±
3
.
1) MeV
/c
2
and its width as Γ
Y
= (32
.
4
±
21
.
0
±
1
.
8) MeV.
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