Topological semimetals with different types of band crossings provide a rich platform to realize novel fermionic excitations, known as topological fermions. In particular, some fermionic excitations ...can be direct analogs of elementary particles in quantum field theory when both obey the same laws of physics in the low-energy limit. Examples include Dirac and Weyl fermions, whose solid-state realizations have provided new insights into long-sought phenomena in high-energy physics. Recently, theorists predicted new types of fermionic excitations in condensed-matter systems without any high-energy counterpart, and their existence is protected by crystalline symmetries. By studying the topology of the electronic structure in PdBiSe using density functional theory calculations and bulk-sensitive soft x-ray angle-resolved photoemission spectroscopy, we demonstrate a coexistence of four different types of topological fermions: Weyl, Rarita-Schwinger-Weyl, double class-II three-component, and charge-2 fourfold fermions. Our discovery provides a remarkable platform to realize multiple fermions in a single solid, charting the way forward to studies of their potentially exotic properties as well as their interplay.
The purpose of this study was to modify the microstructure and mechanical properties of AZ61 cast magnesium alloy via solid-state friction stir processing (FSP). The effect of processing parameters ...on the microstructural evolution, texture and mechanical behavior was investigated. The results indicate that FSP was capable of producing fine-grained AZ61 magnesium alloy through dynamic recrystallization, and eliminating the unfavorable network-like large β-Mg17Al12 particles present along the grain boundaries in the cast magnesium alloy. With increasing ratio of rotation rate to traverse speed, the grain size and fraction of high-angle grain boundaries (HAGBs) increased. Compared with the original cast alloy, the microhardness and tensile properties of FSP specimens were significantly enhanced. The high strength and ductility of FSP specimens were achieved mainly due to the scattered distribution of crystallographic texture and the effective grain refinement along with a larger fraction of HAGBs.
Using 448.0×106 ψ(3686) events collected with the BESIII detector, an amplitude analysis is performed for ψ(3686)→γχc1, χc1→ηπ+π− decays. The most dominant two-body structure observed is a0(980)±π∓; ...a0(980)±→ηπ±. The a0(980) line shape is modeled using a dispersion relation, and a significant nonzero a0(980) coupling to the η′π channel is measured. We observe χc1→a2(1700)π production for the first time, with a significance larger than 17σ. The production of mesons with exotic quantum numbers, JPC=1−+, is investigated, and upper limits for the branching fractions χc1→π1(1400)±π∓, χc1→π1(1600)±π∓, and χc1→π1(2015)±π∓, with subsequent π1(X)±→ηπ± decay, are determined.
A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 × ...10(6) positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ∼ 250 GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.
EIF5A2, eukaryotic translation initiation factor 5A2, is associated with several human cancers. In this study, we investigated the role of EIF5A2 in the metastatic potential of localised invasive ...bladder cancer (BC) and its underlying molecular mechanisms were explored.
The expression pattern of EIF5A2 in localised invasive BC was determined by immunohistochemistry. In addition, the function of EIF5A2 in BC and its underlying mechanisms were elucidated with a series of in vitro and in vivo assays.
Overexpression of EIF5A2 was an independent predictor for poor metastasis-free survival of localised invasive BC patients treated with radical cystectomy. Knockdown of EIF5A2 inhibited BC cell migratory and invasive capacities in vitro and metastatic potential in vivo and reversed epithelial-mesenchymal transition (EMT), whereas overexpression of EIF5A2 promoted BC cells motility and invasiveness in vitro and metastatic potential in vivo and induced EMT. In addition, we found that EIF5A2 might activate TGF-β1 expression to induce EMT and drive aggressiveness in BC cells. EIF5A2 stabilized STAT3 and stimulated nuclear localisation of STAT3, which resulted in increasing enrichment of STAT3 onto TGF-β1 promoter to enhance the transcription of TGF-β1.
EIF5A2 overexpression predicts tumour metastatic potential in patients with localised invasive BC treated with radical cystectomy. Furthermore, EIF5A2 elevated TGF-β1 expression through STAT3 to induce EMT and promotes aggressiveness in BC.
We report the first observation of D+→τ+ντ with a significance of 5.1σ. We measure B(D+→τ+ντ)=(1.20±0.24stat±0.12syst)×10−3. Taking the world average B(D+→μ+νμ)=(3.74±0.17)×10−4, we obtain ...Rτ/μ=Γ(D+→τ+ντ)/Γ(D+→μ+νμ)=3.21±0.64stat±0.43syst., which is consistent with the standard model expectation of lepton flavor universality. Using external inputs, our results give values for the D+ decay constant fD+ and the Cabibbo-Kobayashi-Maskawa matrix element |Vcd| that are consistent with, but less precise than, other determinations.
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•The Ni25 coating was fabricated by laser cladding to repair the damaged components.•LSP treatment was applied on the Ni25 coating for surface strengthening.•Columnar dendrites in the ...top region were transformed into refined equiaxed dendrites.•Influence mechanisms of LSP on the microstructural evolution were revealed.
H13 steel is frequently subjected to the high-strength alternating stress and cyclic thermal load impact, the Ni25 coating was prepared by laser cladding (LC) on the worn surface of H13 tool steel to repair the damaged components. As the residual stress induced by LC in the Ni25 coating, laser shock peening (LSP) was combined to further improve the stress distribution and strengthen the mechanical performance. The influences of LSP treatment on the microstructure and mechanical performance were systematically studied. Results showed that after LSP treatment, columnar dendrites in the surface layer with a depth of 0.28 mm were transformed into refined equiaxed dendrites. Meanwhile, the residual stress was completely converted from tensile state into compressive state, and the micro-hardness was also enhanced by 27.3 %, with the peak of 550 HV. Consequently, the coefficient of friction (COF) and wear rate of Ni25 coating were decreased significantly. Finally, extra attentions were paid to the laser shock wave-induced formation mechanism improvement in wear property of laser cladding Ni25 coating on H13 tool steel.
ABSTRACT
The study of blazar jet has been performed for several decades via VLBI technique, while its generation and propagation stay unclear. In the present work, we compiled a sample of 407 VLBI ...detected Fermi blazars (VFBs) and studied the correlations between apparent velocity (${\rm log}\, \beta _{\rm app}$) and jet/accretion disc properties. We found a positive correlation between γ-ray luminosity (${\rm log}\, L_{\rm \gamma }$) and ${\rm log}\, \beta _{\rm app}$; the correlation suggests that the apparent motion of jet knot is related to the jet power. The correlations between ${\rm log}\, \beta ^{\rm max}_{\rm app}$ and the jet radiation power (${\rm log}\, L_{\rm rad}$), and between ${\rm log}\, \beta ^{\rm max}_{\rm app}$ and the jet extended region luminosity at 5 GHz (${\rm log}\, L_{\rm 5GHz}^{\rm ext}$), which is an indicator of jet kinetic power, reveal that the knots apparent motion is correlated with both jet radiation power and the kinetic power. But this indication is not held for flat-spectrum radio quasar (FSRQs) in terms of the correlation ${\rm log}\, L_{\rm 5GHz}^{\rm ext}\, versus \, {\rm log}\, \beta ^{\rm max}_{\rm app}$. Besides, ${\rm log}\, \beta ^{\rm max}_{\rm app}$ has a moderate correlation with accretion disc luminosity (${\rm log}\, L_{\rm Disk}$) and the normalized accretion disc luminosity ${\rm log}\, (L_{\rm Disk}/L_{\rm Edd})$, which may suggest both the power of accretion disc and the accretion rate are critical to generate knots and to accelerate them. In addition, we found the VFBs have larger average values of γ-ray luminosity (${\rm log}\, L_{\rm \gamma }$), γ-ray photon index (αph), and variability index (${\rm log}\, VI$) than the rest of Fermi blazars. Through Gaussian mixture models method, we generated a criteria, ${\rm log}\, L_{\rm \gamma } \gt 45.40$, αph > 2.24, and ${\rm log}\, VI \gt 1.71$ to find VFB candidates, selected 228 VFB candidates from the rest of Fermi blazar.
To establish an ideal microenvironment for regenerating maxillofacial defects, recent research interests have concentrated on developing scaffolds with intricate configurations and manipulating the ...stiffness of extracellular matrix toward osteogenesis. Herein, we propose to infuse a degradable RGD-functionalized alginate matrix (RAM) with osteoid-like stiffness, as an artificial extracellular matrix, to a rigid 3D-printed hydroxyapatite scaffold for maxillofacial regeneration. The 3D-printed hydroxyapatite scaffold was produced by microextrusion technology and showed good dimensional stability with consistent microporous detail. RAM was crosslinked by calcium sulfate to manipulate the stiffness, and its degradation was accelerated by partial oxidation using sodium periodate. The results revealed that viability of bone marrow stem cells was significantly improved on the RAM and was promoted on the oxidized RAM. In addition, the migration and osteogenic differentiation of bone marrow stem cells were promoted on the RAM with osteoid-like stiffness, specifically on the oxidized RAM. The in vivo evidence revealed that nonoxidized RAM with osteoid-like stiffness upregulated osteogenic genes but prevented ingrowth of newly formed bone, leading to limited regeneration. Oxidized RAM with osteoid-like stiffness facilitated collagen synthesis, angiogenesis, and osteogenesis and induced robust bone formation, thereby significantly promoting maxillofacial regeneration. Overall, this study supported that in the stabilized microenvironment, oxidized RAM with osteoid-like stiffness offered requisite mechanical cues for osteogenesis and an appropriate degradation profile to facilitate bone formation. Combining the 3D-printed hydroxyapatite scaffold and oxidized RAM with osteoid-like stiffness may be an advantageous approach for maxillofacial regeneration.
Using an e+e− collision data sample of 2.93 fb−1 collected at a center-of-mass energy of 3.773 GeV by the BESIII detector at BEPCII, we report the observation of D0→a0(980)−e+νe and evidence for ...D+→a0(980)0e+νe with significances of 6.4σ and 2.9σ, respectively. The absolute branching fractions are determined to be B(D0→a0(980)−e+νe)×B(a0(980)−→ηπ−)=1.33−0.29+0.33(stat)±0.09(syst)×10−4 and B(D+→a0(980)0e+νe)×B(a0(980)0→ηπ0)=1.66−0.66+0.81(stat)±0.11(syst)×10−4. This is the first time the a0(980) meson has been measured in a D0 semileptonic decay, which would open one more interesting page in the investigation of the nature of the puzzling a0(980) states.
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