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Context-free Grammars for Triangular Arrays

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Acta Mathematica Sinica,English Series 2015年第3期31卷 445-455页

作者： Robert x.J.HAO Larry x.w.wang Harold R.L.YANG Center for Combinatorics LPMC-TJKLC Nankai University

we consider context-free grammars of the form G = {f → f^b1＋b2＋1g^a1＋a2, g → f^b1 g^a1＋1},where ai and bi are integers sub ject to certain positivity conditions. Such a grammar G gives rise to triangular arrays {T（n, k）}0≤k≤n satisfying a three-term recurrence relation. Many combinatorial sequences can be generated in this way. Let Tn （x） =∑k=0^n T（n, k）x^k. Based on the differential operator with respect to G, we define a sequence of linear operators Pn such that Tn＋1（x） = Pn（Tn（x））. Applying the characterization of real stability preserving linear operators on the multivariate polynomials due to Borcea and Br？ndén, we obtain a necessary and sufficient condition for the operator Pn to be real stability preserving for any n. As a consequence, we are led to a sufficient condition for the real-rootedness of the polynomials defined by certain triangular arrays, obtained by wang and ***, as special cases we obtain grammars that lead to identities involving the whitney numbers and the Bessel numbers.

关键词： Context-free grammar stable polynomials real-rootedness Bessel numbers whitneynumbers

Compressive property and energy absorption characteristic of interconnected porous Mg-Zn-Y alloys with adjusting Y addition

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Journal of Magnesium and Alloys 2024年第1期12卷 171-185页

作者： J.A.Liu S.J.Liu B.wang w.B.Sun x.J.Liu Z.w.Han College of Materials Science and Engineering Key Laboratory of Automobile Materials(Ministry of Education)Jilin UniversityChangchun 130022PR China Key Laboratory of Bionic Engineering(Ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchun130022PR China weihai Institute for Bionics-Jilin University Weihai 264205PR China

In this study,interconnected porous Mg-2Zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption *** characterization methods were then applied to identify the microstructure of the porous Mg-Zn-Y and describe the details of the second *** tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous *** experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second *** the Y content increases,different Mg-Zn-Y ternary phases appear:I-phase(Mg_(3)Zn_(6)Y),w-phase(Mg_(3)Zn_(3)Y_(2)),and LPSO phase(Mg_(12)ZnY).when the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 MJ/m^(3)to 10.97 MJ/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second ***,the average energy absorption efficiency is independent of the Y *** addition,the compressive deformation behaviors of the porous Mg-Zn-Y are altered by the testing *** compressive strength and energy absorption capacity of the porous Mg-Zn-Y decrease due to the softening effect of the high temperature on the *** deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.

关键词： Porous magnesium Rare earth elements Microstructure Compressive behavior Energy absorption characteristic

Molecular pathogenesis of human hepatocellular carcinoma

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Molecular pathogenesis of human hepatocellular carcinoma

In situ digital testing method for quality assessment of soft soil improvement with polyurethane

中国毒理学会第三届全国学术会议

作者： x.w.wang S.P.Hussain T.I.Huo C.G.wu M.Forgues L.J.Hofseth C.Brechot C.C.Harris Laboratory of Human Carcinogenesis National Cancer InstituteBethesdaMDUSA Laboratory of Human Carcinogenesis National Cancer InstituteBethesdaMDUSA Laboratory of Human Carcinogenesis National Cancer InstituteBethesdaMDUSA Laboratory of Human Carcinogenesis National Cancer InstituteBethesdaMDUSA Laboratory of Human Carcinogenesis National Cancer InstituteBethesdaMDUSA Laboratory of Human Carcinogenesis National Cancer InstituteBethesdaMDUSA Necker Institute ParisFrance Laboratory of Human Carcinogenesis National Cancer InstituteBethesdaMDUSA

＜正＞ Primary hepatocellular carcinoma（HCC） is one of the most com-mon malignancies in the world. However, the viral-chemical etiol-ogy as well as molecular mechanisms of HCC pathogenesis remainslargely unknown. Recent studies in our laboratory have identifiedseveral potential factors that may contribute to the pathogenesis ofHCC. Oxidative stress and chronic inflammation have been linkedto an increased risk of liver cancer. Oxyradical overload diseases,

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1732-1748页

作者： x.F.wang C.J.wang w.V.Yue Z.J.Zhang Z.Q.Yue Department of Civil Engineering China University of Geosciences (Beijing)BeijingChina Department of water Science and Engineering Zhengzhou UniversityZhengzhouChina Department of Geotechnical Engineering Tongji UniversityShanghaiChina Department of Civil Engineering The University of Hong KongChina

This study purposes an in situ testing method on quality assessment of soil *** drilling data includes the spatial distribution and in situ strength of untreated and treated soil along three different drillholes measured by on-site drilling monitoring *** factual drilling data can characterize the degree of soil improvement by penetration injection with permeable *** from on-site drilling monitoring shows that the linear zones represent constant drilling speeds shown in the plot of drill bit advancement *** drilling time,which indicates the spatial distributions of soil *** soil profile at the study site is composed of four layers,which includes fill,untreated silty clay,treated silty clay,and mucky *** results of soil profile are verified by the parallel site *** constant drilling speeds profile the coring-resistant strength of drilled *** comparing with the untreated silty clay,the constant drilling speeds of the treated silty clay have been decreased by 13.0-62.8%.Two drilling-speed-based indices of 61.2%and 65.6%are proposed to assess the decreased average drilling speed and the increased in situ strength of treated silty *** tests,*** compressive strength(UCS)test,have been performed with core sample to investigate and characterize in situ strength by comparing that with drilling *** show that the average predicted strengths of treated silty clay are 2.4-6.9 times higher than the average measured strength of untreated silty *** UCS-based indices of 374.5%and 344.2%verified the quality assessment(QA)results by this new in situ *** method provides a cost-effective tool for quality assessment of soil improvement by utilizing the digital drilling data.

关键词： Drilling process monitoring system Hydraulic rotary drilling process Constant drilling speed Soil improvement Quality assessment

Resistive field generation in intense proton beam interaction with solid targets

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Matter and Radiation at Extremes 2024年第1期9卷 35-43页

作者： w.Q.wang J.J.Honrubia Y.Yin x.H.Yang F.Q.Shao Department of Physics National University of Defense TechnologyHunanChina ETSI Aeronáutica y del Espacio Universidad Politécnica de MadridMadridSpain Department of Nuclear Science and Technology National University of Defense TechnologyHunanChina

The Brown-Preston-Singleton(BPS)stopping power model is added to our previously developed hybrid code to model ion beam-plasma *** simulations show that both resistive field and ion scattering effects are important for proton beam transport in a solid target,in which they compete with each *** the target is not completely ionized,the self-generated resistive field effect dominates over the ion scattering ***,when the target is completely ionized,this situation is ***,it is found that Ohmic heating is important for higher current densities and materials with high *** energy fraction deposited as Ohmic heating can be as high as 20%-30%.Typical ion divergences with half-angles of about 5°-10°will modify the proton energy deposition substantially and should be taken into account.

关键词： interaction beam intense

Precipitation of multi-type nano-quasicrystals in a Mg-Zn-Y alloy

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Journal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： w.Z.wang x.Z.Zhou L.F.Zhang H.Q.Ye Z.Q.Yang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji Hua Laboratory Foshan 528251China Foshan University Foshan 528231China

Mg-6Zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging *** evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy *** new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex Laves Mg-Zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 *** findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： Quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.

Superexchange and charge transfer in the nickelate superconductor La3Ni2O7 under pressure

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Science China(Physics,Mechanics & Astronomy) 2024年第11期Mechanics & Astronomy) .卷 5-12页

作者： wéi wú Zhihui Luo Dao-xin Yao Meng wang Center for Neutron Science and Technology Guangdong Provincial Key Laboratory of Magnetoelectric Physics and DevicesSchool of Physics Sun Yat-sen University

Recently, a bulk nickelate superconductor La3Ni2O7is discovered at pressures with a remarkable high transition temperature Tc～ 80 K. Here, we study a Hubbard model with tight-binding parameters derived from ab initio calculations of La3Ni2O7,by employing large scale determinant quantum Monte Carlo and cellular dynamical mean-field theory. Our result suggests that the superexchange couplings in this system are comparable to that of cuprates. The system is a charge transfer insulator as the hole concentration becomes four per site at large Hubbard U. Upon hole doping, two low-energy spin-singlet bands emerge in the system exhibiting distinct correlation properties: while the one composed of the out-of-plane Ni-d3z2-r2and O-pzorbitals demonstrates strong antiferromagnetic correlations and narrow effective bandwidth, the in-plane singlet band consisting of the Ni-dx2-y2and O-px/pyorbitals is in general more itinerant. Over a broad range of hole doping, the doped holes occupy primarily the dx2-y2and px/pyorbitals, whereas the d3z2-r2and pzorbitals retain underdoped. we propose an effective t-J model to capture the relevant physics and discuss the implications of our result for comprehending the La3Ni2O7superconductivity.

关键词： superconductivity nickelate superconductors Hubbard model superexchange charge transfer insulator quantum Monte Carlo

Fast efficient photon deceleration in plasmas by using two laser pulses at different frequencies

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Matter and Radiation at Extremes 2024年第3期9卷 11-18页

作者： Y.x.wang x.L.Zhu S.M.weng P.Li x.F.Li H.Ai H.R.Pan Z.M.Sheng Key Laboratory for Laser Plasmas(moe) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Research Center of Laser Fusion of China Academy of Engineering Physics MianyangSichuan 621900China State key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Tsung-dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

The generation of ultrashort high-power light sources in the mid-infrared(mid-IR)to terahertz(THz)range is of interest for applications in a number of fields,from fundamental research to biology and *** conventional laser technology,photon deceleration in plasma wakes provides an alternative approach to the generation of ultrashort mid-IR or THz ***,we present a photon deceleration scheme for the efficient generation of ultrashort mid-IR or THz pulses by using an intense driver laser pulse with a relatively short wavelength and a signal laser pulse with a relatively long *** signal pulse trails the driver pulse with an appropriate time delay such that it sits at the front of the second wake bubble that is driven by the driver *** to its relatively long wavelength,the signal pulse will be subjected to a large gradient of the refractive index in the plasma wake ***,the photon deceleration in the plasma wake becomes faster and more efficient for signal pulses with longer *** greatly enhances the capacity and efficiency of photon deceleration in the generation of ultrashort high-power light sources in the long-wavelength IR and THz spectral ranges.

关键词： laser ultrashort photon

Progress on the antiferromagnetic topological insulator MnBi2Te4

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National Science Review 2024年第2期11卷 33-49页

作者： Shuai Li Tianyu Liu Chang Liu Yayu wang Hai-Zhou Lu x.C.xie Department of Physics Harbin Institute of Technology Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology(SUSTech) Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area(Guangdong) Shenzhen Key Laboratory of Quantum Science and Engineering International Quantum Academy Beijing Academy of Quantum Information Sciences Beijing Key Laboratory of Optoelectronic Functional Materials&Micro-Nano Devices Department of Physics Renmin University of China State Key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua University Frontier Science Center for Quantum Information Hefei National Laboratory International Center for Quantum Materials School of Physics Peking University Institute for Nanoelectronic Devices and Quantum Computing Fudan University

Topological materials, which feature robust surface and/or edge states, have now been a research focus in condensed maTher physics. They represent a new class of materials exhibiting nontrivial topological phases,and provide a platform for exploring exotic transport phenomena, such as the quantum anomalous Hall effect and the quantum spin Hall effect. Recently, magnetic topological materials have attracted considerable interests due to the possibility to study the interplay between topological and magnetic *** particular, the quantum anomalous Hall and axion insulator phases can be realized in topological insulators with magnetic order. MnBi2Te4, as the first intrinsic antiferromagnetic topological insulator discovered, allows the examination of existing theoretical predictions; it has been extensively studied, and many new discoveries have been made. Here we review the progress made on MnBi2Te4from both experimental and theoretical aspects. The bulk crystal and magnetic structures are surveyed first, followed by a review of theoretical calculations and experimental probes on the band structure and surface states, and a discussion of various exotic phases that can be realized in MnBi2Te4. The properties of MnBi2Te4thin films and the corresponding transport studies are then reviewed, with an emphasis on the edge state transport. Possible future research directions in this field are also discussed.

关键词： MnBi2Te4 magnetic topological insulator antiferromagnetic quantum anomalous Hall effect axion insulator