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The only purple-flower species in Actaea *** pollinated by a hornet

Journal of Plant Ecology 2024年第4期17卷 181-196页

作者： Lin-Feng Qiu Jiu-Dong zhang Ying Li Xiao-Ying Liu Dan-Qing zhang Long Huang Ya-Peng Yang Shi-Yu Wang Yue-Yi Li Zi-Wei Ma Jie Sui Lin Wang Xiao-Fen Che Xian-Hua Tian Yi Ren jian-qiang zhang National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest China College of Life SciencesShaanxi Normal UniversityXi’an 710119China Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education Shaanxi Normal UniversityXi’an 710119China College of Biological and Environmental Engineering Xi’an UniversityXi’an 710065China

Examining the pollination biology of plant species is not only crucial for enhancing our understanding of their reproductive biology,but also essential for elucidating their adaptation and evolutionary ***,we investigated the breeding system and pollination biology of two closely related species in *** flower of *** is unique in the genus with purple and chartaceous(paper-like)sepals,fewer stamens with yellow anthers and purple *** three seasons of field observation and exclusion experiments,we determined that *** was primarily pollinated by a hornet species,Vespa bicolor,which also served as the most efficient *** contrast,*** was primarily pollinated by large *** purpurea exhibited a significantly higher cumulative nectar volume than ***,which could be a crucial factor in attracting ***.A control experiment further demonstrated that removing the nectar leaf(petal)significantly decreased the visiting frequency of *** system studies revealed that both species were self-compatible,yet they primarily underwent outcrossing in natural *** study presents a compelling case of possible pollinator shift in *** accompanied by morphological divergence.A more in-depth investigation of this system would offer crucial insights into the extent to which pollinators are involved in the plant speciation process and whether they contribute to reproductive isolation between closely related species.

关键词： Actaea purpurea Actaea japonica breeding system pollinator shift speciation Vespa bicolor

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Characteristics of Welding Crack Defects and Failure Mode in Resistance Spot Welding of DP780 Steel

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Journal of Iron and Steel Research International 2016年第10期23卷 1104-1110页

作者： Xiao-pei WANG Yong-qiang zhang jian-bin JU jian-qiang zhang jian-wei YANG Shougang Research Institute of Technology Beijing 100043 China College of Science China University of Petroleum (Beijing) Beijing 102249 China

The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested,and three different types of welding cracks in welded joints were investigated by optical microscopy,scanning electron microscopy and electron back-scattered ***,the failure mode of the welded joints in shear tensile test was *** is found the shear tensile strength of welded joints can be greatly improved by adding preheating current or tempering *** surface crack in welded joint is intergranular fracture,while the inner crack in welded joint is transgranular fracture,and the surface crack on the edge of the electrode imprint can be improved by adding preheating current or tempering *** traditional failure mode criterion advised by American Welding Society is no longer suitable for DP780 spot welds and the critical nugget size suggested by Pouranvari is overestimated.

关键词： resistance spot welding mechanical property crack defect failure mode DP780 steel

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Allopolyploid origin and niche expansion of Rhodiola integrifolia(Crassulaceae)

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Plant Diversity 2023年第1期45卷 36-44页

作者： Da-Lv Zhong Yuan-Cong Li jian-qiang zhang National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest China College of Life SciencesShaanxi Normal UniversityNo.620West Chang’an AvenueChang'an DistrictXi’an710119China

Polyploidy after hybridization between species can lead to immediate post-zygotic isolation,causing saltatory origin of new *** the incidence of polyploidization in plants is high,it is thought that a new polyploid lineage can succeed only if it establishes a new ecological niche divergent from its progenitor *** tested the hypothesis that Rhodiola integrifolia from North America is an allopolyploid produced by R. rhodantha and *** and determined whether its survival can be explained by the niche divergence *** this end,we sequenced two low-copy nuclear genes(ncpGS and rpb2) in a phylogenetic analysis of 42 Rhodiola species and tested for niche equivalency and similarity using Schoener’s D as the index of niche *** phylogeny-based approach showed that R integrifolia possesses alleles from both R. rhodantha and rosea Dating analysis showed that the hybridization event that led to *** occurred ca.1.67 Mya and niche modeling analysis showed that at this time,both *** and *** may have been present in Beringia,providing the opportunity for the hybridization *** also found that the niche of *** differs from that of its progenitors in both niche breadth and *** together,these results confirm the hybrid origin of *** and support the niche divergence hypothesis for this tetraploid *** results underscore the fact that lineages with no current overlapping distribution could produce hybrid descendants in the past,when climate oscillations made their distributions overlap.

关键词： Allopolyploid Hybridization ncpGS Niche shift rpb2 Schoener’s D

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CO_(2) High Temperature Corrosion and Its Prevention of Chromia Forming Fe-base Alloys

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表面技术 2021年第4期50卷 260-266页

作者：张建强 School of Materials Science&Engineering University of New South WalesSydney NSW2052Australia

High temperature corrosion of chromia forming Fe-base alloys by CO_(2) produces not only oxidation but also *** corrosion kinetics in CO_(2)-rich gas is found to be increased compared with that in air or *** a result,higher alloy chromium levels are required to achieve protective chromia formation in CO_(2).Corrosion reaction mechanisms in CO_(2) are examined and the internal carburisation of alloys in low carbon activity CO_(2) gases are analysed based on the variation of pO_(2) at the interface of oxide and *** penetration through chromia oxide scale has been revealed by atom probe *** strategies to resist CO_(2) corrosion are reviewed by alloying of Si and/or Mn,forming additional diffusion barrier layers,and by adding sulphur to modify oxide grain boundaries to reduce carbon diffusion along the grain boundaries.

关键词： high temperature corrosion CO_(2) chromia-forming alloys carburisation alloying

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Effect of CaO/Al2O3 ratio on viscosity and structure of CaO-Al2O3-based fluoride-free mould fluxes

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Journal of Iron and Steel Research International 2019年第4期26卷 374-384页

作者： Qi Wang Ji-an Yang Chen zhang De-xiang Cai jian-qiang zhang Oleg Ostrovski School of Materials Science and Engineering University of New South WalesSydney 2052Australia Baosteel Group Corporation Research Institute Shanghai 201900China

The effects of CaO/Al2O3 ratio on viscosity and structure of the CaO-Al2O3-based fluoride-free mould fluxes were investigated with the CaO/Al2O3 ratio varied from 1 to 4 and the content of SiO2 fixed at 7 wt.%. The increase in the CaO/Al2O3 ratio from 1 to 2 lowered the viscosity of the flux melts. The viscosity increased slightly with the CaO/Al2O3 ratio from 2 to 3, and this increase became significant with further increasing CaO/Al2O3 ratio to 4. Both break temperature and apparent activation energy were found to be increased with the increase in CaO/Al2O3 ratio from 2 to 4. There was no break temperature available in the flux with CaO/Al2O3 ratio of 1. Changing the CaO/Al2O3 ratio from 1 to 2 decreased the apparent activation energy. Equilibrium phases of the fluxes were calculated using FactSage 7.1 and the major phases were found to be varied with the CaO/Al2O3 ratio. Structures of tested mould fluxes were analysed using Fourier transform infrared spectroscopy. The results showed that the increase in the CaO/Al2O3 ratio from 1 to 2 decreased the complexity of the structure, leading to a reduced viscosity. With the increase in the CaO/Al2O3 ratio from 2 to 4, both solid phase precipitation and melt structure contributed to the variation of viscosity.

关键词： CaO-Al2O3-based flux CaO/Al2O3 ratio Viscosity Flux structure

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Symmetrical Independence Tests for Two Random Vectors with Arbitrary Dimensional Graphs

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Acta Mathematica Sinica,English Series 2022年第4期38卷 662-682页

作者： Jia Min LIU Gao Rong LI jian qiang zhang Wang Li XU Center for Applied Statistics Renmin University of ChinaBeijing 100872P.R.China School of Statistics Beijing Normal UniversityBeijing 100875P.R.China

Test of independence between random vectors X and Y is an essential task in statistical *** type of testing methods is based on the minimal spanning tree of variables X and *** main idea is to generate the minimal spanning tree for one random vector X,and for each edges in minimal spanning tree,the corresponding rank number can be calculated based on another random vector *** resulting test statistics are constructed by these rank ***,the existed statistics are not symmetrical tests about the random vectors X and Y such that the power performance from minimal spanning tree of X is not the same as that from minimal spanning tree of *** addition,the conclusion from minimal spanning tree of X might conflict with that from minimal spanning tree of *** order to solve these problems,we propose several symmetrical independence tests for X and *** exact distributions of test statistics are investigated when the sample size is ***,we study the asymptotic properties of the statistics.A permutation method is introduced for getting critical values of the *** with the existing methods,our proposed methods are more efficient demonstrated by numerical analysis.

关键词： Exact distribution minimal spanning tree asymptotic distribution symmetrical independence test

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CRYSTALLIZATION BEHAVIOR, THERMAL AND MECHANICAL PROPERTIES OF PHBV/GRAPHENE NANOSHEET COMPOSITES

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Chinese Journal of Polymer Science 2013年第4期31卷 670-678页

作者： Bing-jie Wang Yu-jie zhang jian-qiang zhang Qu-ting Gou Zong-bao Wang Peng Chen 顾群 Ningbo Institute of Material Technology and Engineering Chinese Academy of Sciences School of Petrochemical Technology Lanzhou University of Technology

Biodegradable poly（3-hydroxybutyrate-co-3-hydroxyvalerate）（PHBV）/graphene nanosheet （GNS） composites were prepared via a solution-casting method at low GNS loadings in this work. Transmission electron microscopy revealed that a fine dispersion of GNSs was achieved in the PHBV matrix. The thermal properties of the nanocomposites were investigated by thermogravimetric analysis, and the results showed that the thermal stability of PHBV was significantly improved with a very low loading of GNSs. Nonisothermal melts crystallization behavior, spherulitic morphology and crystal structure of neat PHBV and the PHBV/GNSs nanocomposites were investigated, and the experimental results indicated that crystallization behavior of PHBV was enhanced by the presence of GNSs due to the heterogeneous nucleation effect; however, the two-dimensional （2D） GNSs might restrict the mobility of the PHBV chains in the process of crystal growing. Dynamic mechanical analysis studies showed that the storage modulus of the PHBV/GNSs nanocomposites was greatly improved.

关键词： PHBV Graphene nanosheets Nanocomposites Solution-casting films.

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An Improved Frequency Synchronizer for Mobile OFDMSystems

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The Journal of China Universities of Posts and Telecommunications 2005年第4期12卷 26-31页

作者： qiang jian-feng zhang ping Department of Telecommunications Engineering Beijing University of Posts and Telecommunications Beijing 100876 P.R. China

Orthogonal Frequency Division Multiplexing （ OFDM） system is sensitive to Carrier Frequency Offset （ CFO ）. In this paper, traditional Maximum Likelihood Estimators （MLE） for CFO of OFDM are introduced first. Then, averaging method and a-filter are introduced as Low Pass Filter （LPF） to improve the performance of cyclic prefix estimator. The bandwith of LPF is determined by the coherence time of radio channel. Estimation performance in multipath channel is analyzed. Outlier picking-out scheme is proposed to improve performance further. Performance of close-loop structure is presented briefly, which is worse than that of open-loop structure. Finally, a parallel switch structure of frequency synchronizer is proposed for mobile OFDM systems. The scheme ezcploits training sequence and cyclic prefix. The proposed synchronizer has a wide acquisition range. It is accurate and robust in both AWGN channel and multipath channels. The complexity is low due to functionality of a-filter. A better performance of frequevlcy synchronization is obtained comparing to that of existing Maximum Likelihood Estimator（ MLEs）. We achieve these advantages without loss of bandwidth efficiency.

关键词： OFDM frequency synchronizer parallel switch structure MLE Low Pass Filter (LPF) open-loop structure

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Subconjunctival conbercept for the treatment of corneal neovascularization

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International Journal of Ophthalmology(English edition) 2023年第6期16卷 871-875页

作者： Cun Sun Fang Ruan Shang Li jian-qiang zhang Ying Jie Department of Ophthalmology Beijing Huimin HospitalBeijing 100053China Department of Ophthalmology Beijing You’an HospitalCapital Medical UniversityBeijing 100054China Beijing Institute of Ophthalmology Beijing Tongren Eye CenterBeijing Tongren HospitalCapital Medical UniversityBeijing Ophthalmology and Visual Sciences Key LabBeijing 100730China

·AIM:To investigate the effectiveness and safety of subconjunctival injection of conbercept in the treatment of corneal neovascularization(CNV).·METHODS:The data on 10 consecutively recruited patients with CNV who received a subconjunctival conbercept(1 mg)once,and measured the area,length,and diameter of neovascularization before and after(1d,1,2wk,and 1mo)treatment as well as the occurrence of systemic and ocular complications after treatment were analyzed.·RESULTS:There was a statistically significant reduction in the area of CNV one day after treatment(mean±SD:38.46±11.36 mm^(2)),compared with before treatment(42.46±12.80 mm^(2),P<0.01).There was also a statistically significant reduction in the length(3.86±1.80 mm vs 4.64±1.77 mm,P<0.01)and diameter(0.044±0.022 vs 0.060±0.026,P<0.05)of CNV,one week after treatment comparing to before *** reduction in all three parameters was maximized at two weeks after treatment(area:29.49±8.83 mm^(2),P<0.001;length:3.50±1.88 mm,P<0.001;and diameter:0.038±0.017 mm,P<0.01).No severe systemic or ocular complication was observed during the study.·CONCLUSION:During the observation period of onemonth,subconjunctival injection of conbercept is an effective and safe method for the reduction of *** may be effective as a preoperative drug for neovascular corneal transplantation.

关键词： KEYWORDS:corneal neovascularization conbercept anti-vascular endothelial growth factor subconjunctival injection

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Accurate simulations of pure-viscoacoustic wave propagation in tilted transversely isotropic media

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Petroleum Science 2024年第2期21卷 866-884页

作者： qiang Mao jian-Ping Huang Xin-Ru Mu Ji-Dong Yang Yu-jian zhang Geosciences Department China University of Petroleum(East China)Qingdao266580ShandongChina Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao266207ShandongChina

Forward modeling of seismic wave propagation is crucial for the realization of reverse time migration(RTM) and full waveform inversion(FWI) in attenuating transversely isotropic media. To describe the attenuation and anisotropy properties of subsurface media, the pure-viscoacoustic anisotropic wave equations are established for wavefield simulations, because they can provide clear and stable wavefields. However, due to the use of several approximations in deriving the wave equation and the introduction of a fractional Laplacian approximation in solving the derived equation, the wavefields simulated by the previous pure-viscoacoustic tilted transversely isotropic(TTI) wave equations has low accuracy. To accurately simulate wavefields in media with velocity anisotropy and attenuation anisotropy, we first derive a new pure-viscoacoustic TTI wave equation from the exact complex-valued dispersion formula in viscoelastic vertical transversely isotropic(VTI) media. Then, we present the hybrid finite-difference and low-rank decomposition(HFDLRD) method to accurately solve our proposed pure-viscoacoustic TTI wave equation. Theoretical analysis and numerical examples suggest that our pure-viscoacoustic TTI wave equation has higher accuracy than previous pure-viscoacoustic TTI wave equations in describing q P-wave kinematic and attenuation characteristics. Additionally, the numerical experiment in a simple two-layer model shows that the HFDLRD technique outperforms the hybrid finite-difference and pseudo-spectral(HFDPS) method in terms of accuracy of wavefield modeling.

关键词： Pure-viscoacoustic TTI wave equation Attenuation anisotropy Seismic modeling Low-rank decomposition method

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