The isothermal local loading forming technology provides a feasible way to form Ti-alloy large-scale rib-web components in aerospace and aviation fields.However,the local loading process forming limit is restricted by...The isothermal local loading forming technology provides a feasible way to form Ti-alloy large-scale rib-web components in aerospace and aviation fields.However,the local loading process forming limit is restricted by forming defects in the transitional region.In this work,the feasibility of controlling forming defects and improving the process forming limit by adjusting die parameters is explored through finite element（FE） simulation.It is found that the common cavum and folding defects in the transitional region are significantly influenced by the fillet radii of left rib and middle rib,respectively.The cavum and folding defects can be effectively controlled by increasing the fillet radii of left rib and middle rib,respectively.The process forming limits considering forming defects in the transitional region are determined by the stepwise searching method under various die parameters.Moreover,the relationship between the process forming limit and die parameters is developed through the response surface methodology（RSM）.The developed RSM models suggest that increasing the fillet radii of left and middle ribs is effective to improve the process forming limit during local loading forming of rib-web components.The results will provide technical basis for the design of die parameters and the reduction amount,which is of great importance to control forming defects and improve the process forming limit in local loading forming of Ti-alloy large-scale rib-web components.展开更多
Polybutene-1(PB-1) is a semi-crystalline polymer with excellent mechanical properties. However, its practical application is significantly hindered by the slow Form Ⅱ-Ⅰ transition, which can take up to several days ...Polybutene-1(PB-1) is a semi-crystalline polymer with excellent mechanical properties. However, its practical application is significantly hindered by the slow Form Ⅱ-Ⅰ transition, which can take up to several days to complete. While prior research established that long-chain branching(LCB) structures synthesized via ω-alkenylmethyldichlorosilane copolymerization-hydrolysis(ACH) chemistry markedly accelerate this transition, this work demonstrates that H-shaped LCB structures constructed through copolymerization with 1,9-decadiene exhibit the capability to facilitate Form Ⅱ-Ⅰ transition in most systems evaluated herein. However, low branching efficiency concurrently generates extended alkyl pendant chains, which impose pronounced steric-hindrance-driven suppression on the transition kinetics, thereby substantially diminishing the net acceleration effect of the LCB structures, even resulting in a net retardation effect in certain systems. Notably, a significant synergistic acceleration effect emerged between the H-shaped LCB structures and propylene comonomer units. These findings confirm that the H-shaped LCB structures play a role in promoting the Form II-I transformation process, which is independent of the synthetic pathways, thereby providing more strategies for addressing the long-standing processing problems of PB-1.展开更多
Several typical ash samples from a 0.25 MW test furnace fired black liquor coal slurry were selected for investigation. The phases and compounds containing sodium in ash samples were acquired from X-ray diffraction an...Several typical ash samples from a 0.25 MW test furnace fired black liquor coal slurry were selected for investigation. The phases and compounds containing sodium in ash samples were acquired from X-ray diffraction analyses. As well, detailed analyses of the amounts of major mineral elements along thickness gradients of representative ash samples were carried out. The elements, including Na, Si, A1, S and C1 were analyzed by the advanced electron probe microanalyzer equipment, which provid evidence and interpretation for the analytical results of XRD. The findings indicate that the occurrence form of sodium has experi- enced important changes during the combustion of black liquor coal slurry, which translated into nepheline, thenardite, sodium sulfate, sodium chloride, sodium silicoaluminate, hanyne and other phases containing sodium, from NaOH, Na2CO3 and Na2S in raw fuel. Of all the sodium compounds, nepheline, thenardite and sodium sulfate are the most important forms of Na in solid com- bustion residues. Such a transformation of Na during the combustion of black liquor coal slurry resulted in a considerable impact on ash deposition and is not only different from the raw coal and papermaldng black liquors, but is also affected by local circum- stances in the combustion furnace. Amounts of Na, S and C1 in ash deposits from low temperature zones were larger than those from high temperature zones. Our findings should provide important theoretical instructions for industrial applications of black liquor coal slurry.展开更多
The phase transition of two kinds of solvent-induced crystalline syndiotactic polystyrene (sPS). gamma-sPS and delta(c)-sPS, has been studied via WAXD and DSC. gamma-sPS transform to a-sPS at 195-225 degrees C before ...The phase transition of two kinds of solvent-induced crystalline syndiotactic polystyrene (sPS). gamma-sPS and delta(c)-sPS, has been studied via WAXD and DSC. gamma-sPS transform to a-sPS at 195-225 degrees C before melt during heating, whereas delta(e)-sPS transform to first gamma-sPS and then a-sPS at 100-200 degrees C and 200-215 degrees C, respectively. The transition of delta(e)-gamma and gamma-a occurs for below melting point of sPS indicates they are all solid-solid transition.展开更多
The present work aims to compare the amorphous phase forming ability of ternary and quaternary Al based alloys （Al86Ni8Y6, Al86GNi6Y6Co2, Al86NigLa6 and Al86Ni8Y45La15） synthesized via mechanical alloying by varying...The present work aims to compare the amorphous phase forming ability of ternary and quaternary Al based alloys （Al86Ni8Y6, Al86GNi6Y6Co2, Al86NigLa6 and Al86Ni8Y45La15） synthesized via mechanical alloying by varying the composition, i.e. fully or partially replacing rare earth （RE） and transition metal （TM） elements based on similar atomic radii and coordination number. X-ray diffraction and high resolution transmission electron microscopy study revealed that the amorphization process occurred through formation of various intermetallic phases and nanocrystalline FCC Al. Fully amorphous phase was obtained for the alloys not containing lanthanum, whereas the other alloys containing La showed partial amorphization with reappearance of intermetallic phases attributed to mechanical crystallization. Differential scanning calorimetry study confirmed better thermal stability with wider transformation temperature for the alloys without La.展开更多
In the paper, we apply the kT factorization approach to deal with the B8 → fofo（980） transition form factors in the large recoil regions, i.e. the small q2 regions. For the purpose, we adopt the B-meson wave-functi...In the paper, we apply the kT factorization approach to deal with the B8 → fofo（980） transition form factors in the large recoil regions, i.e. the small q2 regions. For the purpose, we adopt the B-meson wave-functions ЖB, ЖB and that include the three-Fock states contributions to do our discussion. Although the scalar meson fo（980） is widely perceived as the 4-quark bound state （scenario 2）, but the distribution amplitudes of 4-quark states are still unknown to us, so we adopt 2-quark model （scenario 1） for scalar meson fo（980） in our discussion. By varying the B-meson wave-function parameters within their reasonable regions, we obtain Fo（0） = F＋（0） = 0.20 ± 0.02, FT（O） = 0.24 4± 0.02. Our present results for these form factors are consistent with the light-cone sum rule results obtained in the literature.展开更多
We survey contemporary studies of hadrons and strongly interacting quarks using QCD's Dyson-Schwinger equations, addressing the following aspects: confinement and dynamical chiral symmetry breaking; the hadron spe...We survey contemporary studies of hadrons and strongly interacting quarks using QCD's Dyson-Schwinger equations, addressing the following aspects: confinement and dynamical chiral symmetry breaking; the hadron spectrum; hadron elastic and transition form factors, from small-to large-Q2; parton distribution functions; the physics of hadrons containing one or more heavy quarks; and properties of the quark gluon plasma.展开更多
Syndiotactic polypropylene （sPP） as-spun fiber （sPP1） and drawn fiber （sPP2） were prepared by melt-spinning and melt-spinning/hot-drawing, respectively. The structure transition of the two fibers induced by anne...Syndiotactic polypropylene （sPP） as-spun fiber （sPP1） and drawn fiber （sPP2） were prepared by melt-spinning and melt-spinning/hot-drawing, respectively. The structure transition of the two fibers induced by annealing at different temperatures and the corresponding mechanical properties were subsequently investigated by the combination of Fourier transform infrared spectroscopy （FTIR）, wide-angle X-ray diffraction （WAXD） and tensile testing. The results indicate that the chain conformation and crystal forms of the two sPP fibers are not obviously changed at low annealing temperature （40℃）. With increasing the annealing temperature, the trans-planar conformation and mesophase in sPP1 and sPP2 fibers can be completely transformed to helical conformation and crystal form I under tension. Upon removing the tension, a small amount of mesophase and trans-planar conformation will be regained. The mechanical properties of the annealed fibers are manifestly dependent on their initial structure and the annealing temperature.展开更多
Similar to other heavy flavor mesons,the weak decays of D*_((s))mesons can provide a platform to verify the standard model,explore new physics,and understand the mechanisms of weak interactions.At present,the theoreti...Similar to other heavy flavor mesons,the weak decays of D*_((s))mesons can provide a platform to verify the standard model,explore new physics,and understand the mechanisms of weak interactions.At present,the theoretical and experimental studies on D*_((s))mesons are relatively limited.In addition to the dominant electromagnetic decays,the D*_((s)) weak decays should be feasible to explore the D*_((s)) mesons.In this study,we used the covariant lit-front quark model to study the form factors o the transitions D*_((s)) →π,K,η_(q,s),and then calculated the branching ratios of the semi-leptonic decays D*_((s))→Pe+ve and the non-leptonic decays D*_((s))→PP,PV with P =π,K,η^((,)),V=ρ,K*,Φ,and e=e,μ.The channels D*_(s)^(+)→ηe+ve and D*_(s)^(+)→ηρ^(+) possess the largest branching ratios,which can reach an order of 10^(-6) among these decays,and are most likely to be accessible in experiments at future high-luminosity colliders.Furthermore,we predict and discuss the longitudinal polarization fraction f_(L) and the forwardbackward asymmetry A_(FB) for the considered semi-leptonic D*_(s)decays.展开更多
We present measurements of the γγ＊ → π^0 transition form factor for the momentum transfer range Q^2=4-40 GeV^2 and the γγ＊ → ηc transition form factor for the range Q^2=2-50 GeV^2. The current status of meas...We present measurements of the γγ＊ → π^0 transition form factor for the momentum transfer range Q^2=4-40 GeV^2 and the γγ＊ → ηc transition form factor for the range Q^2=2-50 GeV^2. The current status of measurements of the meson-photon transition form factors for the η and η＇ mesons is discussed. The results of the measurement of the ηc mass, total and two-photon widths are also presented.展开更多
The top predators of arthropods,such as scorpions,spiders,and centipedes,are less commonly discovered in Mesozoic terrestrial Lagerst?tten.Scorpiones belong to the class Arachnida within Arthropoda,with relatively few...The top predators of arthropods,such as scorpions,spiders,and centipedes,are less commonly discovered in Mesozoic terrestrial Lagerst?tten.Scorpiones belong to the class Arachnida within Arthropoda,with relatively few fossil records[1].The earliest scorpions come from the mid Silurian,and at least some of them have been interpreted as transitional forms from sea to land[2].Despite being among the earliest terrestrial arthropods,fossil and living scorpions retain a largely conservative body plan[3].Mesozoic scorpions are mainly from mid-Cretaceous Burmese amber[4],whereas compression fossils of scorpions normally deposited in the strata are relatively rare except in the Late Triassic Keuper Sandstone Formation of England and the Early Cretaceous Crato Formation of Brazil[1].展开更多
In this study,we continue an investigation of the semileptonic decays B_(s)→D_(s)^(*)lve.First,we derive the moments of the D_(s)^(*)-meson longitudinal leading-twist light-cone distribution amplitude (LCDA) based on...In this study,we continue an investigation of the semileptonic decays B_(s)→D_(s)^(*)lve.First,we derive the moments of the D_(s)^(*)-meson longitudinal leading-twist light-cone distribution amplitude (LCDA) based on QCD sum rules within the background field theory framework.Considering the contributions of the vacuum condensates up to dimension-six,its first ten non-zero ξ-moments at the initial scale μ_(0)=1.3GeV are <ξ_(2;D_(s)^(*))^(‖,1)>}μ_(0)=-0.302_(-0.046)^(+0.038),<ξ_(2;D_(s)^(*))^(‖,2)>}μ_(0)=+0.229_(-0.034)^(+0.039),<ξ_(2;D_(s)^(*))^(‖,3)>}μ_(0)=-0.121_(-0.019)^(+0.015),<ξ_(2;D_(s)^(*))^(‖,4)>}μ_(0)=+0.101_(-0.014)^(+0.017),<ξ_(2;D_(s)^(*))^(‖,5)>}μ_(0)=-0.066_(-0.010)^(+0.009),<ξ_(2;D_(s)^(*))^(‖,6)>}μ_(0)=+0.053_(-0.007)^(+0.009),<ξ_(2;D_(s)^(*))^(‖,7)>}μ_(0)=-0.041_(-0.007)^(+0.006),<ξ_(2;D_(s)^(*))^(‖,8)>}μ_(0)=+0.037_(-0.005)^(+0.006),<ξ_(2;D_(s)^(*))^(‖,9)>}μ_(0)=-0.026_(-0.004)^(+0.003),and <ξ_(2;D_(s)^(*))^(‖,10)>}μ_(0)=+0.025_(-0.004)^(+0.004).We also construct the D_(s)^(*)-meson longitudinal leading-twist LCDA by using the light-cone harmonic oscillator model.Then,using the above moments,we fix the model parameters α_(2);D_(s)^(*) and B_(1)^(2;D_(s)^(*)) using the least squares method and apply them to calculate B_(s)→D_(s)^(*) transition form factors A_(1)(q^(2)),A_(2)(q^(2)) and V(q^(2)) that are derived using the QCD light-cone sum rules.In the large recoil region,we obtain A_(1)(0)=0.632_(-0.135)^(+0.228),A_(2)(0)=0.706_(-0.092)^(+0.109),,and V(0)=0.647_(-0.069)^(+0.076).These form factors are then extrapolated to the allowed whole physical q^(2)-region through the simplified series expansion.Finally,we obtain the branching fractions for the two decay channels of B_(s)→D_(s)^(*)lve,B(B_(s)^(0)→D_(s)^(*)e^(-)v_(e))=(5.45_(-1.57)^(+2.15))×10^(-2) and B(B_(s)^(0)→D_(s)^(*)μ^(-)v_(μ))=(5.43_(-1.57)^(+2.14))×10^(-2).In addition,we present the CKM matrix element |V_(cb)| by matching the LHCb Collaboration branching fraction,yielding a value of |V_(cb)|=(40.11+_(7.49)^(+6.54))×10^(-3).展开更多
The dilepton invariant mass spectra and integrated branching ratios of the single and double Dalitz decays P→l^＋l^-γ and P→l^＋l^-l^＋l^-（P=π^0,η,η＇;l=e or μ） are predicted by means of a data-driven approac...The dilepton invariant mass spectra and integrated branching ratios of the single and double Dalitz decays P→l^＋l^-γ and P→l^＋l^-l^＋l^-（P=π^0,η,η＇;l=e or μ） are predicted by means of a data-driven approach based on the use of rational approximants applied to π^0,η and η＇ transition form factor experimental data in the space-like region.展开更多
Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are discussed. The new data confirm the assertion of the symmetric constituent quark model of the Roper as the first radial e...Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are discussed. The new data confirm the assertion of the symmetric constituent quark model of the Roper as the first radial excitation of the nucleon. The data on high Q2 nπ＋ production better constrain the branching ratios liNK and [3Nn. For the first time, the longitudinal transition amplitude to the S11（1535） was extracted from the nπ＋ data. Also, new results on the transition amplitudes for the D13（1520） resonance are presented showing a rapid transition from helicity 3/2 dominance seen at the real photon point to helicty 1/2 dominance at higher Q2. I also discuss the status of the search for new excited nucleon states.展开更多
In this paper,we investigate the charmed meson rare decay process D^(+)→π^(+)v■using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude(DA)moments<ξ_(2)^(n);|μand<ξ3;π(p,σ...In this paper,we investigate the charmed meson rare decay process D^(+)→π^(+)v■using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude(DA)moments<ξ_(2)^(n);|μand<ξ3;π(p,σ),n>|μ,are calculated up to the tenth and fourth orders,respectively,in the QCD sum rules according to the background field theory.After constructing the light-cone harmonic oscillator model for the pion twist-2,3 D As,we obtain their behaviors by matching the calculatedξ-moments.Then,the D→πtransition form factors(TFFs)are calculated using an approach based on QCD light-cone sum rules.The vector form factor at the large recoil region is f_(+)^(D)→^(π)(0)=0.627_(-0.080)^(+0.120).Using the rapidly converging simplified series expansion of z(q^(2),t),we present the TFFs and corresponding angular coefficients in the whole squared momentum transfer physical region.Based on nonstandard neutrino interactions,the■^(0)→π^(+)e■_(e)decay can be related to the■^(0)→π^(+)e■_(e)decay indirectly.Thus,we first describe the semileptonic decay process■^(0)→π^(+)e■_(e),differential decay widths,and branching fraction with B(■^(0)→π^(+)e■_(e))=0.308_(-0.066)^(+0.155)×10^(2).The■^(0)→π^(+)e■_(e)differential/total predictions for forward-backward asymmetry,q^(2)-differential flat terms,and lepton polarization asymmetry are also reported.The prediction for the D^(+)→π^(+)v■branching fraction isB(D^(+)→π^(+)v■)=1.85_(-0.46)+^(0.93)×10^(-8).展开更多
We report the analysis status of single π0electroproduction in the resonance region to study the electromagnetic excitation of the nucleon resonances. The study is aimed at understanding of the internal structure and...We report the analysis status of single π0electroproduction in the resonance region to study the electromagnetic excitation of the nucleon resonances. The study is aimed at understanding of the internal structure and dynamics of the nucleon. The experiment was performed using an unpolarized cryogenic hydrogen target and 2.0 and 5.8 GeV polarized electron beam during the ele and e1-6 run periods with CLAS at Jefferson Lab. The new measurements will produce a data base with high statistics and large kinematic coverage for the hadronic invariant mass （W） up to 2.0 CeV in the momentum transfer （Q2） range of 0.3--6.0 GeV2. Preliminary results will be presented and compared with the various model calculations.展开更多
The unitary isobar model MAID2007 has been used to analyze the recent data of pion electroproduction. The model contains all four-star resonances in the region below W = 2 GeV and both single-Q2 and Q2 dependent trans...The unitary isobar model MAID2007 has been used to analyze the recent data of pion electroproduction. The model contains all four-star resonances in the region below W = 2 GeV and both single-Q2 and Q2 dependent transition form factors could be obtained for the Delta, Roper, D13（1520）, S11 （1535）, S31 （1620）, $11（1650）, D15（1675）, F15（1680） and P13（1720）. From the complete world data base, including also π data on the neutron, also Q2 dependent neutron form factors are obtained. For all transition form factors we also give convenient numerical parameterizations that can be used in other reactions. Furthermore, we show how the transition form factors can be used to obtain empirical transverse charge densities and our first results are given for the Roper, the S11 and D13 resonances.展开更多
The Nambu–Jona-Lasinio model is utilized to investigate the pion-and kaon-photon leading-twist transition distribution amplitudes using proper time regularization.Separately,the properties of the vector and axial vec...The Nambu–Jona-Lasinio model is utilized to investigate the pion-and kaon-photon leading-twist transition distribution amplitudes using proper time regularization.Separately,the properties of the vector and axial vector pion-photon transition distribution amplitudes are examined,and the results meet the desired properties.Our study involves sum rule and polynomiality condition.The vector and axial vector pion-photon transition form factors that are present in theπ^(+)→γe^(+)νprocess are the first Mellin moments of the pion-photon transition distribution amplitudes.The vector transition form factor originates from the internal structure of hadrons,the axial current can be coupled to a pion,this pion is virtual,and its contribution will be present independently of the external hadrons.The kaon transition form factors are similar.The vector form factor's value at zero momentum transfer is determined by the axial anomaly,while this is not the case for the axial one.The vector and axial form factors,as well as the neutral pion vector form factor F_(πγγ)(t),are depicted.According to our findings,the pion axial transition form factor is harder than the vector transition form factor and harder than the electromagnetic form factor.We also discuss the link betweenπ−γandγ−πtransitions distribution amplitudes.展开更多
With the recent investigations of the g＊g＊-η（＇） transition form factor and mixing scheme, we present an updated study of the radiative decays J/ψ→η（＇）γ in perturbative QCD. The decays are taken as a test ...With the recent investigations of the g＊g＊-η（＇） transition form factor and mixing scheme, we present an updated study of the radiative decays J/ψ→η（＇）γ in perturbative QCD. The decays are taken as a test ground for the g＊g＊-η（＇） transition form factors and the η-η＇ mixing scheme. The form factors are found to be working for glunic η＇ production and the mixing angle is constrained to be φ = 35.1°±1 0.8°.展开更多
We present recent investigations on the vector and axial-vector transitions of the baryon antidecuplet within the framework of the self-consistent SU（3） chiral quark-soliton model, taking into account the 1/No rotat...We present recent investigations on the vector and axial-vector transitions of the baryon antidecuplet within the framework of the self-consistent SU（3） chiral quark-soliton model, taking into account the 1/No rotational and linear mscorrections. The main contribution to the electric-like transition form factor comes from the wave-function corrections. This is a consequence of the generalized Ademollo-Gatto theorem. It is also found that in general the leading-order contributions are almost canceled by the rotational 1/No corrections. The results are summarized as follows： the vector and tensor K＇NO coupling constants, gK＊N= 0.74--0.87 and fk＊N =0.53--1.16, respectively, and F→KN = 0.71 MeV, based on the result of the KN coupling constant gKne =0.83. We also show the differential cross sections and beam asymmetries, based on the present results. We also discuss the connection of present results with the original work by Diakonov, Petrov, and Polyakov.展开更多
基金the support of the National Natural Science Foundation of China(Nos.51605388,51675433)111 Project(B08040)+2 种基金the Research Fund of the State Key Laboratory of Solidification Processing(NWPU)in China(Grant No.131-QP-2015)the Fundamental Research Funds for the Central Universitiesthe Open Research Fund of State Key Laboratory of Materials Processing and Die&Mold Technology at Huazhong University of Science and Technology
文摘The isothermal local loading forming technology provides a feasible way to form Ti-alloy large-scale rib-web components in aerospace and aviation fields.However,the local loading process forming limit is restricted by forming defects in the transitional region.In this work,the feasibility of controlling forming defects and improving the process forming limit by adjusting die parameters is explored through finite element（FE） simulation.It is found that the common cavum and folding defects in the transitional region are significantly influenced by the fillet radii of left rib and middle rib,respectively.The cavum and folding defects can be effectively controlled by increasing the fillet radii of left rib and middle rib,respectively.The process forming limits considering forming defects in the transitional region are determined by the stepwise searching method under various die parameters.Moreover,the relationship between the process forming limit and die parameters is developed through the response surface methodology（RSM）.The developed RSM models suggest that increasing the fillet radii of left and middle ribs is effective to improve the process forming limit during local loading forming of rib-web components.The results will provide technical basis for the design of die parameters and the reduction amount,which is of great importance to control forming defects and improve the process forming limit in local loading forming of Ti-alloy large-scale rib-web components.
基金financially supported by the National Natural Science Foundation of China (Nos. 52173013 and 52373015)。
文摘Polybutene-1(PB-1) is a semi-crystalline polymer with excellent mechanical properties. However, its practical application is significantly hindered by the slow Form Ⅱ-Ⅰ transition, which can take up to several days to complete. While prior research established that long-chain branching(LCB) structures synthesized via ω-alkenylmethyldichlorosilane copolymerization-hydrolysis(ACH) chemistry markedly accelerate this transition, this work demonstrates that H-shaped LCB structures constructed through copolymerization with 1,9-decadiene exhibit the capability to facilitate Form Ⅱ-Ⅰ transition in most systems evaluated herein. However, low branching efficiency concurrently generates extended alkyl pendant chains, which impose pronounced steric-hindrance-driven suppression on the transition kinetics, thereby substantially diminishing the net acceleration effect of the LCB structures, even resulting in a net retardation effect in certain systems. Notably, a significant synergistic acceleration effect emerged between the H-shaped LCB structures and propylene comonomer units. These findings confirm that the H-shaped LCB structures play a role in promoting the Form II-I transformation process, which is independent of the synthetic pathways, thereby providing more strategies for addressing the long-standing processing problems of PB-1.
基金Projects 2004CB217701 supported by the National Basic Research Program of China 2005-1 by the Scientific Research Foundation of the Ministry ofEducation of Hebei Province
文摘Several typical ash samples from a 0.25 MW test furnace fired black liquor coal slurry were selected for investigation. The phases and compounds containing sodium in ash samples were acquired from X-ray diffraction analyses. As well, detailed analyses of the amounts of major mineral elements along thickness gradients of representative ash samples were carried out. The elements, including Na, Si, A1, S and C1 were analyzed by the advanced electron probe microanalyzer equipment, which provid evidence and interpretation for the analytical results of XRD. The findings indicate that the occurrence form of sodium has experi- enced important changes during the combustion of black liquor coal slurry, which translated into nepheline, thenardite, sodium sulfate, sodium chloride, sodium silicoaluminate, hanyne and other phases containing sodium, from NaOH, Na2CO3 and Na2S in raw fuel. Of all the sodium compounds, nepheline, thenardite and sodium sulfate are the most important forms of Na in solid com- bustion residues. Such a transformation of Na during the combustion of black liquor coal slurry resulted in a considerable impact on ash deposition and is not only different from the raw coal and papermaldng black liquors, but is also affected by local circum- stances in the combustion furnace. Amounts of Na, S and C1 in ash deposits from low temperature zones were larger than those from high temperature zones. Our findings should provide important theoretical instructions for industrial applications of black liquor coal slurry.
基金the open laboratory funds of Chinese Academy of Sciences.
文摘The phase transition of two kinds of solvent-induced crystalline syndiotactic polystyrene (sPS). gamma-sPS and delta(c)-sPS, has been studied via WAXD and DSC. gamma-sPS transform to a-sPS at 195-225 degrees C before melt during heating, whereas delta(e)-sPS transform to first gamma-sPS and then a-sPS at 100-200 degrees C and 200-215 degrees C, respectively. The transition of delta(e)-gamma and gamma-a occurs for below melting point of sPS indicates they are all solid-solid transition.
基金financial support obtained from the Science and Engineering Research Board,Department of Science & Technology,Government of India(SB/S3/ME/0044/2013)Sponsored Research and Industrial Consultancy,Indian Institute of Technology Kharagpur,India(GAF)
文摘The present work aims to compare the amorphous phase forming ability of ternary and quaternary Al based alloys （Al86Ni8Y6, Al86GNi6Y6Co2, Al86NigLa6 and Al86Ni8Y45La15） synthesized via mechanical alloying by varying the composition, i.e. fully or partially replacing rare earth （RE） and transition metal （TM） elements based on similar atomic radii and coordination number. X-ray diffraction and high resolution transmission electron microscopy study revealed that the amorphization process occurred through formation of various intermetallic phases and nanocrystalline FCC Al. Fully amorphous phase was obtained for the alloys not containing lanthanum, whereas the other alloys containing La showed partial amorphization with reappearance of intermetallic phases attributed to mechanical crystallization. Differential scanning calorimetry study confirmed better thermal stability with wider transformation temperature for the alloys without La.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No.CDJZR10100023
文摘In the paper, we apply the kT factorization approach to deal with the B8 → fofo（980） transition form factors in the large recoil regions, i.e. the small q2 regions. For the purpose, we adopt the B-meson wave-functions ЖB, ЖB and that include the three-Fock states contributions to do our discussion. Although the scalar meson fo（980） is widely perceived as the 4-quark bound state （scenario 2）, but the distribution amplitudes of 4-quark states are still unknown to us, so we adopt 2-quark model （scenario 1） for scalar meson fo（980） in our discussion. By varying the B-meson wave-function parameters within their reasonable regions, we obtain Fo（0） = F＋（0） = 0.20 ± 0.02, FT（O） = 0.24 4± 0.02. Our present results for these form factors are consistent with the light-cone sum rule results obtained in the literature.
基金Supported by the Project of Knowledge Innovation Program of the Chinese Academy of Sciences under Grant No. KJCX2.YW.W10Sistema Nacional de Investigadores+8 种基金CONACyT grant 46614-Fthe University of Adelaide and the Australian Research Council through Grant No. FL0992247Coordinación de la Investigación Científica (UMSNH) under Grant 4.10the U. S. Department of Energy, Office of Nuclear Physics, Grant No. DE-AC02-06CH11357Fundao de Amparo Pesquisa do Estado de So Paulo, Grant Nos. 2009/51296-1 and 2010/05772-3the National Natural Science Foundation of China under Grant Nos. 10425521, 10675002, 10705002, 10935001 and 11075052the Major State Basic Research Development Program, under Grant No. G2007CB815000Forschungszentrum Jülich GmbHthe U. S.National Science Foundation under Grant No. PHY-0903991, in conjunction with a CONACyT Mexico-USA Collaboration Grant
文摘We survey contemporary studies of hadrons and strongly interacting quarks using QCD's Dyson-Schwinger equations, addressing the following aspects: confinement and dynamical chiral symmetry breaking; the hadron spectrum; hadron elastic and transition form factors, from small-to large-Q2; parton distribution functions; the physics of hadrons containing one or more heavy quarks; and properties of the quark gluon plasma.
基金supported by the National Natural Science Foundation of China(No.50603029)the Innovation Foundation of Center for Molecular Science,Chinese Academy of Sciences(CMS-Y200724)
文摘Syndiotactic polypropylene （sPP） as-spun fiber （sPP1） and drawn fiber （sPP2） were prepared by melt-spinning and melt-spinning/hot-drawing, respectively. The structure transition of the two fibers induced by annealing at different temperatures and the corresponding mechanical properties were subsequently investigated by the combination of Fourier transform infrared spectroscopy （FTIR）, wide-angle X-ray diffraction （WAXD） and tensile testing. The results indicate that the chain conformation and crystal forms of the two sPP fibers are not obviously changed at low annealing temperature （40℃）. With increasing the annealing temperature, the trans-planar conformation and mesophase in sPP1 and sPP2 fibers can be completely transformed to helical conformation and crystal form I under tension. Upon removing the tension, a small amount of mesophase and trans-planar conformation will be regained. The mechanical properties of the annealed fibers are manifestly dependent on their initial structure and the annealing temperature.
基金the National Natural Science Foundation of China(11347030)the Program of Science and Technology Innovation Talents in Universities of Henan Province(14HASTIT037)the Natural Science Foundation of Henan Province(232300420116,252300421302)。
文摘Similar to other heavy flavor mesons,the weak decays of D*_((s))mesons can provide a platform to verify the standard model,explore new physics,and understand the mechanisms of weak interactions.At present,the theoretical and experimental studies on D*_((s))mesons are relatively limited.In addition to the dominant electromagnetic decays,the D*_((s)) weak decays should be feasible to explore the D*_((s)) mesons.In this study,we used the covariant lit-front quark model to study the form factors o the transitions D*_((s)) →π,K,η_(q,s),and then calculated the branching ratios of the semi-leptonic decays D*_((s))→Pe+ve and the non-leptonic decays D*_((s))→PP,PV with P =π,K,η^((,)),V=ρ,K*,Φ,and e=e,μ.The channels D*_(s)^(+)→ηe+ve and D*_(s)^(+)→ηρ^(+) possess the largest branching ratios,which can reach an order of 10^(-6) among these decays,and are most likely to be accessible in experiments at future high-luminosity colliders.Furthermore,we predict and discuss the longitudinal polarization fraction f_(L) and the forwardbackward asymmetry A_(FB) for the considered semi-leptonic D*_(s)decays.
文摘We present measurements of the γγ＊ → π^0 transition form factor for the momentum transfer range Q^2=4-40 GeV^2 and the γγ＊ → ηc transition form factor for the range Q^2=2-50 GeV^2. The current status of measurements of the meson-photon transition form factors for the η and η＇ mesons is discussed. The results of the measurement of the ηc mass, total and two-photon widths are also presented.
基金supported by the National Natural Science Foundation of China(41925008 and 42288201)。
文摘The top predators of arthropods,such as scorpions,spiders,and centipedes,are less commonly discovered in Mesozoic terrestrial Lagerst?tten.Scorpiones belong to the class Arachnida within Arthropoda,with relatively few fossil records[1].The earliest scorpions come from the mid Silurian,and at least some of them have been interpreted as transitional forms from sea to land[2].Despite being among the earliest terrestrial arthropods,fossil and living scorpions retain a largely conservative body plan[3].Mesozoic scorpions are mainly from mid-Cretaceous Burmese amber[4],whereas compression fossils of scorpions normally deposited in the strata are relatively rare except in the Late Triassic Keuper Sandstone Formation of England and the Early Cretaceous Crato Formation of Brazil[1].
基金Supported in part by the National Natural Science Foundation of China(12265009,12265010)the Project of Guizhou Provincial Department of Science and Technology(MS[2025]219,CXTD[2025]030,ZK[2023]024)。
文摘In this study,we continue an investigation of the semileptonic decays B_(s)→D_(s)^(*)lve.First,we derive the moments of the D_(s)^(*)-meson longitudinal leading-twist light-cone distribution amplitude (LCDA) based on QCD sum rules within the background field theory framework.Considering the contributions of the vacuum condensates up to dimension-six,its first ten non-zero ξ-moments at the initial scale μ_(0)=1.3GeV are <ξ_(2;D_(s)^(*))^(‖,1)>}μ_(0)=-0.302_(-0.046)^(+0.038),<ξ_(2;D_(s)^(*))^(‖,2)>}μ_(0)=+0.229_(-0.034)^(+0.039),<ξ_(2;D_(s)^(*))^(‖,3)>}μ_(0)=-0.121_(-0.019)^(+0.015),<ξ_(2;D_(s)^(*))^(‖,4)>}μ_(0)=+0.101_(-0.014)^(+0.017),<ξ_(2;D_(s)^(*))^(‖,5)>}μ_(0)=-0.066_(-0.010)^(+0.009),<ξ_(2;D_(s)^(*))^(‖,6)>}μ_(0)=+0.053_(-0.007)^(+0.009),<ξ_(2;D_(s)^(*))^(‖,7)>}μ_(0)=-0.041_(-0.007)^(+0.006),<ξ_(2;D_(s)^(*))^(‖,8)>}μ_(0)=+0.037_(-0.005)^(+0.006),<ξ_(2;D_(s)^(*))^(‖,9)>}μ_(0)=-0.026_(-0.004)^(+0.003),and <ξ_(2;D_(s)^(*))^(‖,10)>}μ_(0)=+0.025_(-0.004)^(+0.004).We also construct the D_(s)^(*)-meson longitudinal leading-twist LCDA by using the light-cone harmonic oscillator model.Then,using the above moments,we fix the model parameters α_(2);D_(s)^(*) and B_(1)^(2;D_(s)^(*)) using the least squares method and apply them to calculate B_(s)→D_(s)^(*) transition form factors A_(1)(q^(2)),A_(2)(q^(2)) and V(q^(2)) that are derived using the QCD light-cone sum rules.In the large recoil region,we obtain A_(1)(0)=0.632_(-0.135)^(+0.228),A_(2)(0)=0.706_(-0.092)^(+0.109),,and V(0)=0.647_(-0.069)^(+0.076).These form factors are then extrapolated to the allowed whole physical q^(2)-region through the simplified series expansion.Finally,we obtain the branching fractions for the two decay channels of B_(s)→D_(s)^(*)lve,B(B_(s)^(0)→D_(s)^(*)e^(-)v_(e))=(5.45_(-1.57)^(+2.15))×10^(-2) and B(B_(s)^(0)→D_(s)^(*)μ^(-)v_(μ))=(5.43_(-1.57)^(+2.14))×10^(-2).In addition,we present the CKM matrix element |V_(cb)| by matching the LHCb Collaboration branching fraction,yielding a value of |V_(cb)|=(40.11+_(7.49)^(+6.54))×10^(-3).
基金Supported by the FPI scholarship BES-2012-055371(S.G-S)the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya under grant 2014 SGR 1450+3 种基金the Ministerio de Ciencia e Innovación under grant FPA2011-25948,the Ministerio de Economía y Competitividad under grants CICYT-FEDER-FPA 2014-55613-P and SEV-2012-0234the Spanish Consolider-Ingenio 2010 Program CPAN(CSD2007-00042)the European Commission under program FP7-INFRASTRUCTURES-2011-1(283286)Support from the CAS President's International Fellowship Initiative for Young International Scientist(2017PM0031)
文摘The dilepton invariant mass spectra and integrated branching ratios of the single and double Dalitz decays P→l^＋l^-γ and P→l^＋l^-l^＋l^-（P=π^0,η,η＇;l=e or μ） are predicted by means of a data-driven approach based on the use of rational approximants applied to π^0,η and η＇ transition form factor experimental data in the space-like region.
文摘Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are discussed. The new data confirm the assertion of the symmetric constituent quark model of the Roper as the first radial excitation of the nucleon. The data on high Q2 nπ＋ production better constrain the branching ratios liNK and [3Nn. For the first time, the longitudinal transition amplitude to the S11（1535） was extracted from the nπ＋ data. Also, new results on the transition amplitudes for the D13（1520） resonance are presented showing a rapid transition from helicity 3/2 dominance seen at the real photon point to helicty 1/2 dominance at higher Q2. I also discuss the status of the search for new excited nucleon states.
基金Supported in part by the National Natural Science Foundation of China(12265010,12265009)the Project of Guizhou Provincial Department of Science and Technology(ZK[2021]024,ZK[2023]142)。
文摘In this paper,we investigate the charmed meson rare decay process D^(+)→π^(+)v■using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude(DA)moments<ξ_(2)^(n);|μand<ξ3;π(p,σ),n>|μ,are calculated up to the tenth and fourth orders,respectively,in the QCD sum rules according to the background field theory.After constructing the light-cone harmonic oscillator model for the pion twist-2,3 D As,we obtain their behaviors by matching the calculatedξ-moments.Then,the D→πtransition form factors(TFFs)are calculated using an approach based on QCD light-cone sum rules.The vector form factor at the large recoil region is f_(+)^(D)→^(π)(0)=0.627_(-0.080)^(+0.120).Using the rapidly converging simplified series expansion of z(q^(2),t),we present the TFFs and corresponding angular coefficients in the whole squared momentum transfer physical region.Based on nonstandard neutrino interactions,the■^(0)→π^(+)e■_(e)decay can be related to the■^(0)→π^(+)e■_(e)decay indirectly.Thus,we first describe the semileptonic decay process■^(0)→π^(+)e■_(e),differential decay widths,and branching fraction with B(■^(0)→π^(+)e■_(e))=0.308_(-0.066)^(+0.155)×10^(2).The■^(0)→π^(+)e■_(e)differential/total predictions for forward-backward asymmetry,q^(2)-differential flat terms,and lepton polarization asymmetry are also reported.The prediction for the D^(+)→π^(+)v■branching fraction isB(D^(+)→π^(+)v■)=1.85_(-0.46)+^(0.93)×10^(-8).
基金Supported by U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-FG-04ER41309in part through Contract No. DE-AC05-060R23177, under which Jefferson Science Associates operates Jefferson Lab
文摘We report the analysis status of single π0electroproduction in the resonance region to study the electromagnetic excitation of the nucleon resonances. The study is aimed at understanding of the internal structure and dynamics of the nucleon. The experiment was performed using an unpolarized cryogenic hydrogen target and 2.0 and 5.8 GeV polarized electron beam during the ele and e1-6 run periods with CLAS at Jefferson Lab. The new measurements will produce a data base with high statistics and large kinematic coverage for the hadronic invariant mass （W） up to 2.0 CeV in the momentum transfer （Q2） range of 0.3--6.0 GeV2. Preliminary results will be presented and compared with the various model calculations.
基金Supported by Deutsche Forschungsgemeinschaft through SFB 443joint Russian-German Heisenberg-Landau program
文摘The unitary isobar model MAID2007 has been used to analyze the recent data of pion electroproduction. The model contains all four-star resonances in the region below W = 2 GeV and both single-Q2 and Q2 dependent transition form factors could be obtained for the Delta, Roper, D13（1520）, S11 （1535）, S31 （1620）, $11（1650）, D15（1675）, F15（1680） and P13（1720）. From the complete world data base, including also π data on the neutron, also Q2 dependent neutron form factors are obtained. For all transition form factors we also give convenient numerical parameterizations that can be used in other reactions. Furthermore, we show how the transition form factors can be used to obtain empirical transverse charge densities and our first results are given for the Roper, the S11 and D13 resonances.
基金Supported by the Scientific Research Foundation of Nanjing Institute of Technology(YKJ202352)the Natural Science Foundation of Jiangsu Province,China(BK20191472)the China Postdoctoral Science Foundation(2022M721564)。
文摘The Nambu–Jona-Lasinio model is utilized to investigate the pion-and kaon-photon leading-twist transition distribution amplitudes using proper time regularization.Separately,the properties of the vector and axial vector pion-photon transition distribution amplitudes are examined,and the results meet the desired properties.Our study involves sum rule and polynomiality condition.The vector and axial vector pion-photon transition form factors that are present in theπ^(+)→γe^(+)νprocess are the first Mellin moments of the pion-photon transition distribution amplitudes.The vector transition form factor originates from the internal structure of hadrons,the axial current can be coupled to a pion,this pion is virtual,and its contribution will be present independently of the external hadrons.The kaon transition form factors are similar.The vector form factor's value at zero momentum transfer is determined by the axial anomaly,while this is not the case for the axial one.The vector and axial form factors,as well as the neutral pion vector form factor F_(πγγ)(t),are depicted.According to our findings,the pion axial transition form factor is harder than the vector transition form factor and harder than the electromagnetic form factor.We also discuss the link betweenπ−γandγ−πtransitions distribution amplitudes.
基金Supported by National Natural Science Foundation of China (10735080,11075059)
文摘With the recent investigations of the g＊g＊-η（＇） transition form factor and mixing scheme, we present an updated study of the radiative decays J/ψ→η（＇）γ in perturbative QCD. The decays are taken as a test ground for the g＊g＊-η（＇） transition form factors and the η-η＇ mixing scheme. The form factors are found to be working for glunic η＇ production and the mixing angle is constrained to be φ = 35.1°±1 0.8°.
基金Supported by Inha University Research Grant (INHA-37453)The work of S.i.N. is supported by NSC96-2112-M033-003-MY3 from the National Science Council (NSC) of Taiwan
文摘We present recent investigations on the vector and axial-vector transitions of the baryon antidecuplet within the framework of the self-consistent SU（3） chiral quark-soliton model, taking into account the 1/No rotational and linear mscorrections. The main contribution to the electric-like transition form factor comes from the wave-function corrections. This is a consequence of the generalized Ademollo-Gatto theorem. It is also found that in general the leading-order contributions are almost canceled by the rotational 1/No corrections. The results are summarized as follows： the vector and tensor K＇NO coupling constants, gK＊N= 0.74--0.87 and fk＊N =0.53--1.16, respectively, and F→KN = 0.71 MeV, based on the result of the KN coupling constant gKne =0.83. We also show the differential cross sections and beam asymmetries, based on the present results. We also discuss the connection of present results with the original work by Diakonov, Petrov, and Polyakov.
