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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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双圆弧斜齿齿轮泵转子加工刀轨规划及仿真

机械设计与制造 2024年第3期 214-217,223页

作者：董庆伟周群起李阁强刘理想河南科技大学机电工程学院河南洛阳471003

针对双圆弧斜齿齿轮泵转子加工方法中存在的加工效率和精度比较低等问题,提出了利用球头铣刀在数控铣床上加工双圆弧斜齿齿轮泵转子的方法。研究目标是:根据双圆弧斜齿齿轮泵转子方程,结合空间啮合原理,建立了双圆弧斜齿轮的加工坐标系... 详细信息

针对双圆弧斜齿齿轮泵转子加工方法中存在的加工效率和精度比较低等问题,提出了利用球头铣刀在数控铣床上加工双圆弧斜齿齿轮泵转子的方法。研究目标是:根据双圆弧斜齿齿轮泵转子方程,结合空间啮合原理,建立了双圆弧斜齿轮的加工坐标系,根据各坐标系之间的转换矩阵,建立了双圆弧斜齿齿轮泵转子的齿面方程,模拟使用球头铣刀进行加工过程,计算出加工刀具中心在平面和空间轨迹,同时给出判定球头铣刀不发生干涉的最大半径的方法。利用VERICUT软件建立虚拟制造环境并进行铣齿仿真加工,验证了双圆弧斜齿齿轮泵转子齿面数控加工方法的正确性及其可行性。

关键词：双圆弧斜齿齿轮泵齿轮建模球头铣刀仿真加工

Four-way radial waveguide power divider with high power-handling capacity

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The Journal of China Universities of Posts and Telecommunications 2011年第5期18卷 124-128页

作者： ZHANG Jian-qiong liu Qing-xiang li xiang-qiang ZHAO liu School of Physical Science and Technology Southwest Jiaotong University Chengdu 610031 China

In this paper, a novel four-way radial waveguide power divider with low insertion loss and high power-handling capacity is proposed. This power divider consists of an input coaxial waveguide, a eentral probe, a radial waveguide, four equispaced identical coupling probes, four equispaced identical adjusting posts and four output coaxial waveguides. The novel coupling probes and the adjusting posts are used to realize favorable uniform power division. A power divider with the center frequency of 4.1 GHz is designed, fabricated and measured. Good agreement between simulation and experiment is noted. The measured 15 dB return-loss bandwidth of the power divider is about 600 MHz. The measured 0.5 dB insertion loss bandwidth is wider than 700 MHz. The differences and isolations between the output ports are also discussed. The power-handling capacity of the power divider is analyzed through simulation, and the result proves its usability in high power applications.

关键词： power divider high power low loss multiport radial waveguide

Multilayered gradient CrN/ZrN coatings synthesized by magnetron sputtering

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中国有色金属学会会刊：英文版 2004年第Z1期14卷 243-246页

作者： liu Feng WANG Ming-xia liu Qian-xiang li De-jun College of Physics and Electronic Information Science Tianjin Normal University Tianjin 300074 China Institute of Plasma Physics Chinese Academy of Science Hefei 230031 China College of Physics and Electronic Information ScienceTianjin Normal University Tianjin 300074 China College of Physics and Electronic Information ScienceTianjin Normal University Tianjin 300074 China College of Physics and Electronic Information ScienceTianjin Normal University Tianjin 300074 China

The multilayer gradient CrN/ZrN coatings were synthesized by a dual cathode DC magnetron *** influence of different species of reaction gases and partial pressures on structure and mechanical properties was investigated using XRD, AES, XPS, and nanoindentation. The results show that N2-NH3 mixture process gas is of benefit to the synthesis of superhard multilayered gradient CrN/ZrN coatings. The presence of the preferred orientations of CrN(111), (200) and ZrN (111), (220) in the structure is a main reason for superhardness of multilayered gradient coatings.

关键词： magnetron sputtering multilayered gradient coating CrN/ZrN nanoindentation

Effect of herbicide acetochlor on cytochrome P450 monooxygenases and GST of earthworms Eisenia fetida

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Journal of Environmental Sciences 2006年第1期18卷 135-140页

作者： XIAO Neng-wen liu xiang-hui li Wei GE Feng State Key Lab of Integrated Management of Pest Insects and Rodents Institute of Zoology Chinese Academy of Sciences Beijing 100080 China

To assess the sublethal toxicity of the herbicide acetochlor to earthworms and to find out biomarkers possible inducted under acetochlor exposure, Eiseniafetida was exposed to artificial soils supplemented with different concentrations of acetochlor（5, 10, 20, 40 and 80 mg/kg soil）. Effects of the acetochlor on cytochrome P450 monooxygenases p-nitroanisole O-demethylase（ODM）, aldrin epoxidase（AE） and glutathione-S-transferases （GSTs） activities were determined. The results revealed cytochrome P450 monooxygenases were elevated with increasing concentrations of acetochlor, and the AE activity increased significantly compared with control at the concentration of 80 mg/kg （P〈0.05）. However, ODM activity from E. fetida was not induced significantly by acetochlor at all treatments（P〉0.05）. Sodium dodecyl sulfate-polyacryamide gel electrophoresis（SDS-PAGE） showed that one protein band was visualized and no evident differences were found in protein profiles between treatments and control. The GST activity increased significantly with longer duration（P〈0.05） and increasing concentrations of acetochlor exposure（P〈0.05）. This study showed that the monooxygenases and GSTs activities in E. fetida could be induced by acetochlor, and thus, the AE and GST could be used in sublethal assays for soil contamination surveys and GST could be used as biomarkers of acetochlor exposure in E. fetida.

关键词： acetochlor Eiseniafetida p-nitroanisole O-demethylase aldrin epoxidase GST

Effect of Reduction in Iodine Content of Edible Salt on the Iodine Status of the Chinese Population

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Biomedical and Environmental Sciences 2018年第9期31卷 645-653页

作者： HE Qian SU Xiao Hui liu Peng FAN li Jun MENG Fan Gang liu li xiang li Ming liu Shou Jun Institute for Iodine Deficiency Disorders Control Center for Endemic Disease Control Chinese Center for Disease Control and Prevention Harbin Medical University

Objective The aim of this study was to evaluate the impact of the revised Chinese National Standard GB26878-2011 ＇Iodine Content in Edible Salt＇ on the iodine status among the Chinese population. Methods In 2011 and 2014, the probability proportionate to size sampling（PPS） was used in each Chinese province to obtain the representative data. In each sampling unit, school children aged 8-10 years and pregnant women were selected. Key indicators included urinary iodine concentration（UIC）, thyroid volume（TV）, and the iodine content in edible household salt. Results The median urinary iodine concentration（MUIC） decreased between 2011 and 2014 from 238.6 to 197.9 μg/L in school-age children. The number of provinces with iodine excess decreased to zero. The proportion of children whose UIC was 〉 300 μg/L was 18.8% and decreased to 11% compared with 29.8% in 2011. There was no significant difference in UIC 〈 50 μg/L between 2014（4.3%） and 2011（3.7%）（P 〉 0.05）. The MUIC among pregnant women in 2014 was more concentrated between 110 and 230 μg/L. The goiter rate among children aged 8-10 years was unchanged, both the goiter rate of 2011 and 2014 remaining below 5%, in view of the sustainable elimination of iodine deficiency disorders. Conclusion The National Standard GB26878-2011 ＇Iodine Content in Edible Salt＇ that was introduced in March 2012 resulted in an overall improvement in iodine status, reducing the risk of excessive iodine intake in the Chinese population.

关键词： Urinary iodine concentration Thyroid volume PPS method

Localization−delocalization transitions in non-Hermitian Aharonov−Bohm cages

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Frontiers of physics 2024年第3期19卷 39-50页

作者： xiang li Jin liu Tao liu School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

A unique feature of non-Hermitian systems is the extreme sensitivity of the eigenspectrum to boundary conditions with the emergence of the non-Hermitian skin effect (NHSE). A NHSE originates from the point-gap topology of complex eigenspectrum, where an extensive number of eigenstates are anomalously localized at the boundary driven by nonreciprocal dissipation. Two different approaches to create localization are disorder and flat-band spectrum, and their interplay can lead to the anomalous inverse Anderson localization, where the Bernoulli anti-symmetric disorder induces mobility in a full-flat band system in the presence of Aharonov−Bohm (AB) Cage. In this work, we study the localization−delocalization transitions due to the interplay of the point-gap topology, flat band and correlated disorder in the one-dimensional rhombic lattice, where both its Hermitian and non-Hermitian structures show AB cage in the presence of magnetic flux. Although it remains the coexistence of localization and delocalization for the Hermitian rhombic lattice in the presence of the random anti-symmetric disorder, it surprisingly becomes complete delocalization, accompanied by the emergence of NHSE. To further study the effects from the Bernoulli anti-symmetric disorder, we found the similar NHSE due to the interplay of the point-gap topology, correlated disorder and flat bands. Our anomalous localization−delocalization property can be experimentally tested in the classical physical platform, such as electrical circuit.

关键词： non-Hermitian skin effects disorder flat band localization−delocalization transition

Removal of Cr(Ⅵ)by glutaraldehyde-crosslinked chitosan encapsulating microscale zero-valent iron:Synthesis,mechanism,and longevity

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Journal of Environmental Sciences 2024年第8期142卷 115-128页

作者： Yijun Duan Fang liu xiang liu Miao li School of Environment Tsinghua UniversityBeijing 100084China Transportation Institute of Inner Mongolia University Hohhot 010070China

Microscale zero-valent iron(mZVI)has shown great potential for groundwater Cr(Ⅵ)***,low Cr(Ⅵ)removal capacity caused by passivation restricted the wide use of *** prepared mZVI/GCS by encapsulating mZVI in a porous glutaraldehydecrosslinked chitosan matrix,and the formation of the passivation layer was alleviated by reducing the contact between zero-valent iron *** average pore diameter of mZVI/GCS was 8.775 nm,which confirmed the mesoporous characteristic of this *** of batch experiments demonstrated that mZVI/GCS exhibited high Cr(Ⅵ)removal efficiency in a wide range of pH(2-10)and temperature(5-35℃).Common groundwater coexisting ions slightly affected m ZVI/*** material showed great reusability,and the average Cr(Ⅵ)removal efficiency was 90.41%during eight *** this study,we also conducted kinetics and isotherms ***-second-order model was the most matched kinetics *** Cr(Ⅵ)adsorption process was fitted by both Langmuir and Freundlich isotherms models,and the maximum Langmuir adsorption capacity of m ZVI/GCS reached243.63 mg/g,which is higher than the adsorption capacities of materials reported in most of the previous ***,the column capacity for Cr(Ⅵ)removal of a mZVI/GCS-packed column was 6.4 times higher than that of a mZVI-packed column in a 50-day ***,mZVI/GCS with a porous structure effectively relieved passivation problems of mZVI and showed practical application prospects as groundwater Cr(Ⅵ)remediation material with practical application prospects.

关键词： Chitosan Glutaraldehyde mZVI Cr(Ⅵ) Groundwater

Time Series and Spatial Epidemiological Analysis of the Prevalence of Iodine Deficiency Disorders in China

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Biomedical and Environmental Sciences 2022年第8期35卷 735-745页

作者： FAN li Jun GAO Yun Yan MENG Fan Gang liu Chang liu Lan Chun DU Yang liu li xiang li Ming SU Xiao Hui liu Shou Jun liu Peng Institute of lodine DeficiencyDisorders Center for Endemic Disease ControlChinese Center forDisease Control and PreventionHarbin Medical UniversityHarbin 150081HeilongjiangChina National Health Commission&Education Bureau of Heilongjiang Province Key laboratory of Etiology and EpidemiologyHarbin Medical UniversityHarbin 150081HeilongjiangChina

Objective To recognize the spatial and temporal characteristics of iodine deficiency disorders(IDD),China national IDD surveillance data for the years of 1995–2018 were *** Time series analysis was used to describe and predict the IDD related indicators,and spatial analysis was used to analyze the spatial distribution of salt iodine *** In China,the median urinary iodine concentration increased in 1995–1997,then decreased to adequate levels,and are expected to remain appropriate in 2019–*** goiter rate continually decreased and is expected to be maintained at a low *** 2002,the coverage rates of iodized salt and the consumption rates of qualified iodized salt(the percentage of qualified iodized salt in all tested salt) increased and began to decline in 2012;they are expected to continue to *** epidemiological analysis indicated a positive spatial correlation in 2016–2018 and revealed feature regarding the spatial distribution of salt related indicators in coastal areas and areas near iodine-excess *** Iodine nutrition in China showed gradual ***,a recent decline has been observed in some areas following changes in the iodized salt supply in *** the future,more regulations regarding salt management should be issued to strengthen IDD control and prevention measures,and avoid the recurrence of IDD.

关键词： Salt iodine lodine deficiency disorders Time series analysis Space epidemiology Reform for the salt industry system