The quantum entangled J/ψ→Σ^{+}Σover ¯^{-} pairs from (1.0087±0.0044)×10^{10} J/ψ events taken by the BESIII detector are used to study the nonleptonic two-body weak decays Σ^{+}→nπ^{+} and Σover ...¯^{-}→nover ¯π^{-}. The CP-odd weak decay parameters of the decays Σ^{+}→nπ^{+} (α_{+}) and Σover ¯^{-}→nover ¯π^{-} (αover ¯_{-}) are determined to be 0.0481±0.0031_{stat}±0.0019_{syst} and -0.0565±0.0047_{stat}±0.0022_{syst}, respectively. The decay parameter αover ¯_{-} is measured for the first time, and the accuracy of α_{+} is improved by a factor of 4 compared to the previous results. The simultaneously determined decay parameters allow the first precision CP symmetry test for any hyperon decay with a neutron in the final state with the measurement of A_{CP}=(α_{+}+αover ¯_{-})/(α_{+}-αover ¯_{-})=-0.080±0.052_{stat}±0.028_{syst}. Assuming CP conservation, the average decay parameter is determined as ⟨α_{+}⟩=(α_{+}-αover ¯_{-})/2=-0.0506±0.0026_{stat}±0.0019_{syst}, while the ratios α_{+}/α_{0} and αover ¯_{-}/αover ¯_{0} are -0.0490±0.0032_{stat}±0.0021_{syst} and -0.0571±0.0053_{stat}±0.0032_{syst}, where α_{0} and αover ¯_{0} are the decay parameters of the decays Σ^{+}→pπ^{0} and Σover ¯^{-}→pover ¯π^{0}, respectively.
The microstructure of the stirred zone (SZ) resulting from friction stir processing or welding (FSP/FSW) has usually been assumed to be uniform when discussing the mechanical properties. However, ...numerous works have indicated that the fine-grained microstructures in the SZ were non-uniform, with precipitate, texture and grain size gradients caused by the severe plastic deformation and heat distribution. In this work commercial aluminum alloy 5083-H112 was subjected to FSP and fine-grained microstructures with an average grain sizes of 2.7–13.4
μm were obtained by controlling the FSP conditions. The stress–strain curves exhibited stepped yield point elongation, which was suggested to be associated with these characteristic non-uniform microstructures. Tensile tests indicated that the Hall–Petch relationship held in this FSP alloy when taking account of the average grain size. Toughness analysis indicated that the optimum toughness was anticipated to be obtained around a grain size of ∼1
μm for this FSP alloy.
•All annealed specimens are composed of α and β phases.•Grain size and phase fraction are greatly dependent on annealing temperature.•Trends of tensile properties with microstructural parameters were ...revealed.•A new strategy for strength-microstructure is developed.
The Ti–Zr–Al–V (TZAV) series alloys having good mechanical properties are potential structural material to apply in the aerospace industry. The strengthening mechanism of those two-ductile phase TZAV alloys with basketweave (BW) microstructure is crucial to their applications in aerospace industry. As a representative of the TZAV series alloys, Ti–30Zr–5Al–3V (TZAV-30) alloy is used for the strengthening mechanism research of TZAV series alloys with BW microstructure. Various heat treatments were designed to obtain different microstructure and tensile properties. XRD patterns show that all heat treated TZAV-30 specimens are wholly composed by two ductile phases, namely, α phase and β phase, no other phase, such as intermetallic compound, is detected. SEM images show that microstructures of all heat treated TZAV-30 specimens are typical BW microstructures. Results show that strength of the TZAV-30 alloy with BW microstructure is greatly dependent on the thickness of the plate α phase and volume fraction of the retained β phase, but nearly independent on the original β phase grain size. A new strategy to determine the microstructure-strength relationship by focusing on the strength of typical two-ductile-phase alloys with BW microstructures is developed. This relationship can be used to analyze the major influencing factors of strength and to forecast the trend of strength in alloys with various BW microstructures.
We report the measurement of the inclusive cross sections for e^{+}e^{-}→nOCH (where nOCH denotes non-open charm hadrons) with improved precision at center-of-mass (c.m.) energies from 3.645 to ...3.871 GeV. We observe three resonances: R(3760), R(3780), and R(3810) with significances of 8.1σ, 13.7σ, and 8.8σ, respectively. The R(3810) state is observed for the first time, while the R(3760) and R(3780) states are observed for the first time in the nOCH cross sections. Two sets of resonance parameters describe the energy-dependent line shape of the cross sections well. In set I set II, the R(3810) state has mass (3805.7±1.1±2.7) (3805.7±1.1±2.7) MeV/c^{2}, total width (11.6±2.9±1.9) (11.5±2.8±1.9) MeV, and an electronic width multiplied by the nOCH decay branching fraction of (10.9±3.8±2.5) (11.0±3.4±2.5) eV. In addition, we measure the branching fractions BR(3760)→nOCH=(25.2±16.1±30.4)%(6.4±4.8±7.7)% and BR(3780)→nOCH=(12.3±6.6±8.3)%(10.4±4.8±7.0)% for the first time. The R(3760) state can be interpreted as an open-charm (OC) molecular state, but containing a simple four-quark state component. The R(3810) state can be interpreted as a hadrocharmonium state.
Based on data samples collected with the BESIII detector at the BEPCII collider, the process e^{+}e^{-}→Σ^{+}Σover ¯^{-} is studied at center-of-mass energies sqrts=2.3960, 2.6454, and 2.9000 GeV. ...Using a fully differential angular description of the final state particles, both the relative magnitude and phase information of the Σ^{+} electromagnetic form factors in the timelike region are extracted. The relative phase between the electric and magnetic form factors is determined to be sinΔΦ=-0.67±0.29(stat)±0.18(syst) at sqrts=2.3960 GeV, ΔΦ=55°±19°(stat)±14°(syst) at sqrts=2.6454 GeV, and 78°±22°(stat)±9°(syst) at sqrts=2.9000 GeV. For the first time, the phase of the hyperon electromagnetic form factors is explored in a wide range of four-momentum transfer. The evolution of the phase along with four-momentum transfer is an important input for understanding its asymptotic behavior and the dynamics of baryons.
•Jet impingement with MEPCM slurry is studied experimentally.•Latent heat of PCM core enhances the heat transfer of slurry compared with water.•Slurry behaves a high-efficiency heat transfer when jet ...distance is from 4 to 9.3.•Heat transfer enhancement is limited when the mass fraction of slurry is too high.•Optimum jet inlet temperature is lower than melting peak temperature of PCM core.
Based on the heat dissipation requirement of high heat flux for electronic chips, this paper establishes a closed-cycle experimental system and investigates jet impingement heat transfer characteristics with a microencapsulated phase change material (MEPCM) slurry as the working fluid. The phase change properties of the MEPCM particles and the thermal properties of the MEPCM slurry are analysed. The effects of several key parameters on the heat transfer and pressure drop of jet impingement are also discussed. Experimental results show that a 10% mass fraction of MEPCM slurry may enhance jet heat transfer by 32.8% compared with water because of the latent heat absorption of the PCM core. The heat transfer enhancement will be limited for higher mass fractions of slurry. The slurry exhibits a high heat transfer efficiency when the jet distance is ΔL/D = 4–9.3. The convective heat transfer coefficient of the slurry first increases and then decreases as the jet inlet temperature increases, and the optimum jet inlet temperature is approximately 12.1 °C lower than the melting peak temperature. Jet temperatures that are too high or too low will lead to deterioration of heat transfer for the slurry. These findings can provide guidance for the design of heat dissipation systems using MEPCM slurries.
Using (10087±44)×10^{6} J/ψ events collected with the BESIII detector, numerous Ξ^{-} and Λ decay asymmetry parameters are simultaneously determined from the process J/ψ→Ξ^{-}Ξover ...¯^{+}→Λ(pπ^{-})π^{-}Λover ¯(nover ¯π^{0})π^{+} and its charge-conjugate channel. The precisions of α_{Λ0} for Λ→nπ^{0} and αover ¯_{Λ0} for Λover ¯→nover ¯π^{0} compared to world averages are improved by factors of 4 and 1.7, respectively. The ratio of decay asymmetry parameters of Λ→nπ^{0} to that of Λ→pπ^{-}, ⟨α_{Λ0}⟩/⟨α_{Λ-}⟩, is determined to be 0.873±0.012_{-0.010}^{+0.011}, where the first and the second uncertainties are statistical and systematic, respectively. The ratio is smaller than unity more than 5σ, which signifies the existence of the ΔI=3/2 transition in Λ for the first time. Besides, we test for CP symmetry in Ξ^{-}→Λπ^{-} and in Λ→nπ^{0} with the best precision to date.
Martensitic phases are intermediate phases in Ti alloys and have obvious effects on microstructure and properties of heat treated specimens. The martensitic transformation and phase stability of Ti ...alloys with high content Zr were investigated. The addition of high content Zr was found to greatly modify the β phase stability and martensitic transformation of Ti alloys. The β transus temperature of Ti–50Zr binary alloy is about 616°C. Simultaneously, the phase composition of the β quenched Ti–50Zr binary alloy is composed of whole α′ martensitic phase. Reversely, the Ti–30Zr–10Al–3.5V and Ti–50Zr–10Al–3.5V quaternary alloys have the higher β transus temperatures 779 and 636°C, respectively. However, phase composition is major α″ martensitic phase in β quenched Ti–30Zr–10Al–3.5V alloy and is major β phase in β quenched Ti–50Zr–10Al–3.5V alloy, respectively. This interesting martensitic transformation phenomenon does not conform to previous wide accepted martensitic transformation theories and laws of Ti alloys. The delayed martensitic transformation of aforementioned two quaternary alloys was considered to be caused by the local stresses resulting from the extra additions of Al and V alloying elements.
Dielectronic recombination (DR) rate coefficients for carbon-like 40Ca14+ forming nitrogen-like 40Ca13+ have been measured using the electron-ion merged-beam technique at the heavy-ion storage ring ...CSRm at the Institute of Modern Physics in Lanzhou, China. The measured DR rate coefficients in the energy range from 0 to 92 eV cover most of the DR resonances associated with 2s22p2 → 2s22p2 and 2s22p2 → 2s2p3 core transitions (ΔN = 0). Theoretical calculations of the DR cross sections were carried out by using two different state-of-the-art atomic theoretical techniques, multiconfiguration Breit-Pauli (MCBP) code AUTOSTRUCTURE and relativistic configuration interaction code FAC, to compare with the experimental rate coefficients. The theoretical calculations agree with the experimental results at collision energy higher than 10 eV. However, significant discrepancies of resonance energies and strengths can be found at collision energy below 8 eV. Temperature-dependent plasma recombination rate coefficients were derived from the measured DR rate coefficients in the energy range from 0.1 to 1000 eV and compared with the recommended atomic data from the literature. The theoretical data of Gu et al. and Zatsarinny et al. are 30% lower than the experimental results at the temperatures of photoionized plasmas, but have a very good agreement at the temperatures of collisionally ionized plasmas. Other previously published theoretical data of Jacobs et al. and Mazzotta et al. by using Burgess formula and LS-coupling calculations significantly underestimate the plasma rate coefficients in the low temperature range. The present results comprise a set of benchmark data suitable for astrophysical modeling.
Apple replant disease (ARD) caused by the fungal pathogen
f. sp.
(
) MR5 brings annual losses to apple production within China. However, the genomic information of the pathogen is not yet available. ...Here, we obtained the whole-genome sequence of the highly virulent
MR5 using the Illumina PE150 platform. The genome size was 42.76 Mb and consisted of 9,047 genes. The GC content was 48.80%, and several genes potentially associated with pathogenicity were identified, such as carbohydrate-active enzymes, secreted proteins, and secondary metabolite gene clusters. There were 260 specific virulence factor genes, mainly related to fungal vegetative growth and the production of cell wall-degrading enzymes. These data will aid future studies investigating host-pathogen interactions and help us develop suitable disease management strategies.
