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Alternative relay regulates the adenosine triphosphatase activity of Locusta migratoria striated muscle myosin

Insect Science 2024年第2期31卷 435-447页

作者： Jie Hao Chang liu Ning Zhang Jing li Tong Ni Mingbo Qu xiang-dong li State Key Laboratory oflntegrated Management of lnsect Pests and Rodents Insttute of ZoologyChinese Academy of SciencesBejingChina University of Chinese Academy of Sciences BejingChina School of Bioengeering Dalian University of TechnologyDalianChina

Locust(Locusta migratoria)has a single striated muscle myosin heavy chain(Mhc)gene,which contains 5 clusters of alternative exclusive exons and 1 differently included penultimate *** alternative exons of Mhc gene encode 4 distinct regions in the myosin motor domain,that is,the N-terminal SH3-like domain,one lip of the nucleotide-binding pocket,the relay,and the ***,we investigated the role of the alternative regions on the motor function of locust muscle *** Sf9-baculovirus protein expression system,we expressed and purified 5 isoforms of the locust muscle myosin heavy meromyosin(HMM),including the major isoform in the thorax dorsal longitudinal flight muscle(FL1)and 4 isoforms expressed in the abdominal intersegmental muscle(AB1 to AB4).Among these 5 HMMs,FL1-HMM displayed the highest level of actin-activated adenosine triphosphatase(ATPase)activity(hereafter referred as ATPase activity).To identify the alternative region(s)responsible for the elevated ATPase activity of FL1-HMM,we produced a number of chimeras of FL1-HMM and *** with the relay of AB4-HMM(encoded by exon-14c)substantially decreased the ATPase activity of FL1-HMM,and conversely,the relay of FL1-HMM(encoded by exon-14a)enhanced the ATPase activity of *** showed that the exon-14a-encoded residues Gly474 and Asn509 are responsible for the elevated ATPase activity of *** results indicate that the alternative relay encoded by exon-14a/c play a key role in regulating the ATPase activity of FL1-HMM and AB4-HMM.

关键词： alternative splicing ATPase Locusta migratoria molecular motor muscle myosin

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The youngest X-ray binaries

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Research in Astronomy and Astrophysics 2020年第10期20卷 221-228页

作者： xiang-dong li School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210023China

Several X-ray binaries(XRBs)have been identified to be associated with supernova remnants(SNRs).Because of the short lifetimes of SNRs,this leaves them to be the youngest known *** small group of binaries provides valuable information on the formation of compact stars under the framework of massive binary *** this paper we review the observational characteristics of these youngest XRBs and discuss their possible implications on the initial conditions of compact stars and their interaction with the companion stars.

关键词： accretion,accretion disks stars:black holes stars:neutron,evolution

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W-entropy formulas on super Ricci flows and Langevin deformation on Wasserstein space over Riemannian manifolds Dedicated to Professor Zhiming Ma on His Seventieth Birthday

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Science China Mathematics 2018年第8期61卷 1385-1406页

作者： Songzi li xiang-dong li School of Mathematical Sciences Beijing Normal University Beijing 100875 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China School of Mathematical Sciences University of Chinese Academy of Sciences Beijing 100049 China

In this survey paper, we give an overview of our recent works on the study of the W-entropy for the heat equation associated with the Witten Laplacian on super-Ricci flows and the Langevin deformation on the Wasserstein space over Riemannian manifolds. Inspired by Perelman's seminal work on the entropy formula for the Ricci flow, we prove the W-entropy formula for the heat equation associated with the Witten Laplacian on n-dimensional complete Riemannian manifolds with the CD(K, m)-condition, and the W-entropy formula for the heat equation associated with the time-dependent Witten Laplacian on n-dimensional compact manifolds equipped with a(K, m)-super Ricci flow, where K ∈ R and m ∈ [n, ∞]. Furthermore, we prove an analogue of the W-entropy formula for the geodesic flow on the Wasserstein space over Riemannian *** result improves an important result due to Lott and Villani(2009) on the displacement convexity of the Boltzmann-Shannon entropy on Riemannian manifolds with non-negative Ricci curvature. To better understand the similarity between above two W-entropy formulas, we introduce the Langevin deformation of geometric flows on the tangent bundle over the Wasserstein space and prove an extension of the W-entropy formula for the Langevin deformation. We also make a discussion on the W-entropy for the Ricci flow from the point of view of statistical mechanics and probability theory. Finally, to make this survey more helpful for the further development of the study of the W-entropy, we give a list of problems and comments on possible progresses for future study on the topic discussed in this survey.

关键词： W-entropy Witten Laplacian Langevin deformation (K,m)-super Ricci flows

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On Be/X-ray binaries with an intermediate-mass black hole

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Research in Astronomy and Astrophysics 2010年第7期10卷 672-680页

作者： Tao li xiang-dong li Department of Astronomy Nanjing University Nanjing 210093 China Key Laboratory of Modern Astronomy and Astrophysics （Nanjing University） Ministry of Education Nanjing 210093 China

We adopt the tidal truncation model proposed by Negueruela and Okazaki for Be/X-ray binaries to investigate the influence of intermediate-mass black holes （IMBHs） on Be-star disks. We show that the viscous decretion disks around Be stars are generally truncated ineffectively under the tidal force of IMBHs. Combining this with observations of Be/X-ray binaries, we suggest that Be/IMBH X-ray binaries may appear as recurrent luminous X-ray transients with quasi-periodic X-ray outbursts.

关键词： black hole physics -- circumstellar matter -- stars emission-line, Be -- X-rays binaries

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On the torque exerted by a warped, magnetically threaded accretion disk

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Research in Astronomy and Astrophysics 2021年第3期21卷 15-20页

作者： Chang liu xiang-dong li School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Key laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210023

Most astrophysical accretion disks are likely to be *** X-ray binaries,the spin evolution of an accreting neutron star is critically dependent on the interaction between the neutron star magnetic field and the accretion *** have been extensive investigations on the accretion torque exerted by a coplanar disk that is magnetically threaded by the magnetic field lines from the neutron stars,but relevant works on warped/tilted accretion disks are still *** this paper we develop a simplified twocomponent model,in which the disk is comprised of an inner coplanar part and an outer,tilted *** on standard assumption on the formation and evolution of the toroidal magnetic field component,we derive the dimensionless torque and show that a warped/titled disk is more likely to spin up the neutron star compared with a coplanar *** also discuss the possible influence of various initial parameters on the torque.

关键词： accretion accretion disks magnetic field X-ray binaries

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On pulsar-driven mass ejection in low-mass X-ray binaries

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Research in Astronomy and Astrophysics 2011年第12期11卷 1457-1468页

作者： Lei Fu xiang-dong li Department of Astronomy Nanjing University Nanjing 210093 China Key Laboratory of Modem Astronomy and Astrophysics Ministry of Education Nanjing 210093 China

There is accumulating evidence for mass ejection in low-mass X-ray binaries （LMXBs） driven by radio pulsar activity during X-ray quiescence. We consider the condition for mass ejection by comparing the radiation pressure from a millisecond pulsar, and the gas pressure at the inner Lagrange point or at the surrounding accretion disk. We calculate the critical spin period of the pulsar below which mass ejection is allowed. Combining with the evolution of the mass transfer rate, we present constraints on the orbital periods of the systems. We show that mass ejection could happen in both wide and compact LMXBs. It may be caused by transient accretion due to thermal instability in the accretion disks in the former, and irradiation-driven mass-transfer cycles in the latter.

关键词： pulsars: general- binaries: general

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Evolution of low-mass X-ray binaries:dependence on the massof the compact object

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Research in Astronomy and Astrophysics 2012年第10期12卷 1417-1426页

作者： Qian Xu Tao li xiang-dong li Department of Astronomy Nanjing University Nanjing 210093 China Key Laboratory of Modern Astronomy and Astrophysics Ministry of Education NanjingUniversity Nanjing 210093 China

We perform numerical calculations to simulate the evolution of low-mass X-ray binary systems. For the accreting compact object we consider the initial mass of 1.4, 10, 20, 100, 200, 500 and 1000 Mo, corresponding to neutron stars （NSs）, stellar- mass black holes （BHs） and intermediate-mass BHs. Mass transfer in these binaries is driven by nuclear evolution of the donors and/or orbital angular momentum loss due to magnetic braking and gravitational wave radiation. For the different systems, we determine their bifurcation periods Pbif that separate the formation of converging systems from the diverging ones, and show that Pbif changes from ~ 1 d to ≥ 3 d for a 1 Mo donor star, with increasing initial accretor mass from 1.4 to 1000 Mo. This means that the dominant mechanism of orbital angular momentum loss changes from magnetic braking to gravitational radiation. As an illustration we compare the evolution of binaries consisting of a secondary star of 1 Mo at a fixed initial period of 2 d. In the case of the NS or stellar-mass BH accretor, the system evolves to a well-detached He white dwarf-neutron star/black hole pair, but it evolves to an ultra- compact binary if the compact object is an intermediate-mass BH. Thus the binary evolution heavily depends upon the mass of the compact object. However, we show that the final orbital period-white dwarf mass relation found for NS low-mass X-ray binaries is fairly insensitive to the initial mass of the accreting star, even if it is an intermediate-mass BH.

关键词： binaries: close -- stars: evolution -- stars: neutron -- X-ray: binaries

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Populations of Bright X-ray Sources in the Starburst Galaxies NGC 4038/4039

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Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 389-396页

作者： Xi-Wei liu xiang-dong li Department of Astronomy Nanjing University Nanjing 210093

Assuming a naive star formation history, we construct synthetic X-ray source populations, using a population synthesis code, for comparison with the observed X-ray luminosity function （XLF） of the interacting galaxies NGC 4038/4039. We have included highand intermediate-mass X-ray binaries, young rotation-powered pulsars and fallback disk-fed black holes in modeling the bright X-ray sources detected. We find that the majority of the X-ray sources are likely to be intermediate-mass X-ray binaries, but for typical binary evolu- tion parameters, the predicted XLF seems to be steeper than observed. We note that the shape of the XLFs depends critically on the existence of XLF break for young populations, and suggest super-Eddington accretion luminosities or the existence of intermediate-mass black holes to account for the high luminosity end and the slope of the XLF in NGC 4038/4039.

关键词： binaries close - galaxies individual (NGC 4038/4039) - stars evolution -X-ray binaries

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Unifying neutron star sub-populations in the supernova fallback accretion model

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Research in Astronomy and Astrophysics 2019年第3期19卷 111-122页

作者： Bai-Sheng liu xiang-dong li Department of Astronomy Nanjing University Key Laboratory of Modern Astronomy and Astrophysics Nanjing University Ministry of Education Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences

We employ the supernova fallback disk model to simulate the spin evolution of isolated young neutron stars(NSs). We consider the submergence of the NS magnetic fields during the supercritical accretion stage and its succeeding reemergence. It is shown that the evolution of the spin periods and the magnetic fields in this model is able to account for the relatively weak magnetic fields of central compact objects and the measured braking indices of young pulsars. For a range of initial parameters, evolutionary links can be established among various kinds of NS sub-populations including magnetars, central compact objects and young pulsars. Thus, the diversity of young NSs could be unified in the framework of the supernova fallback accretion model.

关键词： accretion,accretion disks一stars neutron,evolution,rotation,magnetic field,magnetars一pulsars general

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Effect of vanadium content on microstructure and properties of in situ TiC reinforced V_(x)FeCoNiCu multi-principal-element alloy matrix composites

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Journal of Iron and Steel Research International 2021年第11期28卷 1471-1480页

作者： Chun-lei Tu Xiao-dong Sun Jie li He-guo Zhu xiang-dong li College of Mechanical Engineering Southeast UniversityNanjing 210094JiangsuChina Special Equipment Safety Supervision Inspection Institute of Jiangsu Province Nanjing 210036JiangsuChina College of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina

V_(x)FeCoNiCu high entropy alloy matrix composites reinforced by in situ TiC particles(10 vol.%),i.e.,V_(x)FeCoNiCu/TiC composites,were fabricated from V–Fe–Co–Ni–Cu–Ti–C system using vacuum inductive melting *** the content of vanadium increasing,the size of TiC particles decreased ***,vanadium agglomeration occurred *** reaction mechanism of the mixed powder(Fe,V,Ti and C)and the mechanical properties of obtaining V_(x)FeCoNiCu/TiC composites were *** was found that three reactions occurred(Fe-Ti-FeTi-Fe_(2)Ti,FeTi-Fe_(2)Ti-Fe-Ti and Ti-C-TiC)in the heating *** apparent activation energy for these three reactions was calculated and found to be 26.4,698.3 and 1879.0 kJ/mol,*** room temperature,tensile strength and elongation increased first and then decreased with the increase in vanadium content and the microhardness increased *** maximum tensile strength of the composites was determined to be 666 MPa,representing a 17.7%increase over that of FeCoNiCu/TiC high entropy alloy composites.

关键词： High entropy alloy matrix composite Vacuum inductive melting Reaction mechanism Apparent activation energy Tensile strength

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