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Research on frequency-temperature compensated sapphire-SrTiO_3 loaded cavity for hydrogen maser

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Journal of Systems Engineering and Electronics 2009年第4期20卷 711-717页

作者： Wang Nuanrang Zhou Tiezhong gao lianshan Yang Chuntao Feng Keming National Key Lab. of Metrology and Calibration Technology Beijing 100854 P. R. China Beijing Inst. of Radio Metrology & Measurement Beijing 100854 P. R. China

To obtain frequency-temperature compensation in a sapphire loaded cavity for hydrogen maser, a dielectric named SrTiO3 is employed whose temperature coefficient of permittivity is opposite to that of sapphire. Based on theoretical analysis and computer simulation, a TE011 mode of a sapphire loaded cavity associated with two small rings of SrTiO3 with different thickness is solved, and the useful parameters that influence the temperature coefficient of cavity are calculated. Finally an experiment is brought forward and its results are very close to the computing results. When the thickness of SiTiO3 dielectric is 7 mm and the diameter is 17 mm in configuration b, the temperature coefficient of cavity is decreased from -58.8 kHz/K to -8.2 kHz/K and the quality factor is 40248.

关键词： atomic hydrogen maser frequency-temperature compensation sapphire loaded cavity temperature coefficient.

Technology and test results of space adaptability of passive hydrogen maser

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Journal of Systems Engineering and Electronics 2017年第2期28卷 251-256页

作者： Hefei Zheng lianshan gao Keming Feng Jing Li Wenming Wang Chunyan Cao Jihong Zhang Beijing Institute of Radio Metrology and Measurement Beijing 100854 China The Second Academy of China Aerospace Science and Industry Corporation Beijing 100854 China

Based on the operating principle and the electric property design of the passive hydrogen maser, the technology and test results of its space adaptability are carried out under the special launch conditions and space environment. The various perturbations affecting the output frequency of such a standard used for the navigation satellite system are specified, such as magnetic field change, vibration, thermal vacuum and radiation. Through the adaptability technology in the aspects above, the security and reliability of the space passive hydrogen maser sufficiently fulfill the requirements of space operation. At present, the space passive hydrogen maser is working normally on board, indicating that the space adaptability satisfies the design requirement.

关键词： passive hydrogen maser space adaptability performance test

Progress on Sapphire Hydrogen Maser for Beidou Navigation System

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Progress on Sapphire Hydrogen Maser for Beidou Navigation Sy...

Analytical analysis method of Whispering Gallery Mode of sapphire dielectric resonators and the optimization of the Q value in liquid helium temperature

第四届中国卫星导航学术年会

作者： Zhou Tiezhong Wu qiong Huang jian gao lianshan Beijing University of Aeronautics&Astronautics Beijing Institute of Radio Metrology & Measurement Beijing Institute of Radio Metrology&Measurement

Active hydrogen maser is one of the most important equipments for the Beidou Navigation system. The stability of active hydrogen maser does influence the synchronize accuracy of time and frequency between the satellites and the ground devices. In order to improve the stability of Sapphire Hydrogen Maser, we had done several improvements on the physical package and electrical package, which include magnetic shield improvements, developing a method to probe the hydrogen atom beam, getter pump improvement and cavity auto-turning system researching. The factor of magnetic shield has been improved to above 105 . We had researched several kinds of getter materials which can improve the lifetime of physical package. We had designed a new form of getter pump, which make the volume of physical package smaller than ever. The stability of the maser after improvement can get 3.1×10-13 @1s, 2.9×10-15 @1day.

关键词： Hydrogen maser· Magnetic shield· Improvement· Beam controlling· Frequency stability

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Analytical analysis method of Whispering Gallery Mode of sap...

New Research Progress in Active Hydrogen Maser in BIRMM

第九届中国卫星导航学术年会

作者： Xi Zhu Haibo Chen Kai Huang lianshan gao Beijing Institute of Radio Metrology and Measurement

A novel approximate analytical method is presented for calculating parameters of Whispering Gallery Mode(WGM) in a sapphire dielectric resonator(SDR). It is based on ray optics and wave theory. The frequency of WGM is computed with less computation time and the influence of sapphire’s parameters on the frequency is also analyzed. The Q value of SDR in the liquid helium temperature is optimized by adjusting the coupling coefficient and the surface roughness of the sapphire. According to the computed results, a SDR employing WGM at X-Band is fabricated. The loaded Q value reaches 4.0×10 and the eigen frequency is 9.205 GHz in the liquid helium temperature.

关键词： Sapphire dielectric resonator Q value Oscillator Whispering gallery mode eigen frequency

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New Research Progress in Active Hydrogen Maser in BIRMM

第十一届中国卫星导航年会

作者： Tiezhong Zhou Mengzhi Wang Shiqing Ren Qiong Wu Xiumei Wang Chenyuan Zhang Chunyan Cao Yaxuan Liu Liang Wang lianshan gao Beijing Institute of Radio Metrology & Measurement(BIRMM)

The active hydrogen maser is a core piece of equipment for the timefrequency *** stability and reliability directly influence system *** optimization of temperature coefficients for

关键词： Time and frequency Active hydrogen maser Cavity Improvement Temperature coefficient Frequency stability

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不同结构盒栅式电子倍增器模拟计算

真空科学与技术学报 2019年第8期39卷 709-713页

作者：王运佳王一非高连山北京无线电计量测试研究所

利用CST三维电磁仿真软件对不同结构的盒栅式电子倍增器进行建模,采用控制变量的分析思想,模拟计算不同打拿极结构下的电子倍增器内电场分布、电子运动轨迹和倍增增益。数值仿真结果显示,不同结构打拿极电子倍增器内部电场稍有不同,并... 详细信息

利用CST三维电磁仿真软件对不同结构的盒栅式电子倍增器进行建模,采用控制变量的分析思想,模拟计算不同打拿极结构下的电子倍增器内电场分布、电子运动轨迹和倍增增益。数值仿真结果显示,不同结构打拿极电子倍增器内部电场稍有不同,并且导致倍增效益有所不同。在具有相同路径的8级打拿极结构的情况下,增益效果由强到弱的顺序为多边形、方形、弧形、三角形。多边形打拿极在二次电子发射材料镀膜区域不同的情况下,电子倍增器的增益效果具有很大的差异。

关键词：盒栅式电子倍增器电子轨迹电子倍增器增益 CST模拟计算

Local magnetic moment oscillation around an Anderson impurity on graphene

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 192-201页

作者： Shuai Li Zhen Ma Jin-Hua gao School of Science Hebei University of Science and Technology School of Electronics and Information Zhengzhou University of Light Industry School of Physics and Wuhan National High Magnetic Field Center Huazhong University of Science and Technology

We theoretically investigate the spin resolved Friedel oscillation （FO） and quasiparticle interference （QPI） in graphene induced by an Anderson *** the impurity becomes magnetic,the resulted FO becomes spin dependent,which gives rise to a local magnetic moment oscillation with an envelop decaying as r-2in real space in the doping ***,at half filling,the electron density and local magnetic moment will not oscillate but decay as *** spin resolved FO has both sublattice and spin ***,the local magnetic moment decay at half filling only occurs at one sublattice of graphene,which is quite like the phenomenon observed in the STM experiment (***ález-Herrero et al.,Science 352,437 （2016）).We further give an analytic formula about such spin dependent FO based on the stationary phase ***,we study the interference of quasiparticles around the magnetic impurity by calculating the spin dependent Fourier-transformed local density of states （FT-LDOS）.Our work gives a comprehensive understanding about the local magnetic moment oscillation around an Anderson impurity on graphene.

关键词： Friedel oscillation local magnetic moment graphene Anderson impurity

核酸疫苗pcDNA3.1-EG95的构建及在绵羊胎儿成纤维细胞中的表达

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生物技术通报 2010年第11期26卷 134-136,152页

作者：杨娇馥王志钢高连山郝慧芳李志伟李洁湛奎内蒙古大学生命科学学院哺乳动物生殖生物学与生物技术教育部重点实验室呼和浩特010021 鄂尔多斯职业学院鄂尔多斯017200

克隆细粒棘球蚴EG95基因cDNA并构建核酸疫苗pcDNA3.1-EG95。根据GenBank中细粒棘球蚴EG95基因序列(AF134378)设计引物并在上游引物起始密码子前加上Kozak序列(CCACC),提取细粒棘球蚴总RNA,RT-PCR扩增目的基因EG95cDNA,扩增片段克隆到pcD... 详细信息

克隆细粒棘球蚴EG95基因cDNA并构建核酸疫苗pcDNA3.1-EG95。根据GenBank中细粒棘球蚴EG95基因序列(AF134378)设计引物并在上游引物起始密码子前加上Kozak序列(CCACC),提取细粒棘球蚴总RNA,RT-PCR扩增目的基因EG95cDNA,扩增片段克隆到pcDNA3.1(+)中构建重组载体pcDNA3.1-EG95后测序。重组质粒pcDNA3.1-EG95采用脂质体法转染绵羊胎儿成纤维细胞并用G418筛选,RT-PCR检测稳定转染细胞中目的基因的转录。测序结果表明克隆的目的基因包含了471bp的完整ORF并与载体连接正确。RT-PCR检测表明EG95基因在稳定转染的绵羊胎儿成纤维细胞中得到转录。成功构建pcDNA3.1-EG95核酸疫苗并可在绵羊胎儿成纤维细胞中转录目的基因,可进一步用于活体动物免疫研究。

关键词：细粒棘球蚴 EG95基因核酸疫苗

Investigating Müller glia reprogramming in mice: a retrospective of the last decade, and a look to the future

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Neural Regeneration Research 2025年第4期20卷 946-959页

作者： Zhiyuan Yin Jiahui Kang Xuan Cheng Hui gao Shujia Huo Haiwei Xu Key Lab of Visual Damage and Regeneration&Restoration of Chongqing Southwest Eye HospitalSouthwest HospitalThird Military Medical University(Army Medical University)ChongqingChina

Müller glia,as prominent glial cells within the retina,plays a significant role in maintaining retinal homeostasis in both healthy and diseased *** lower vertebrates like zebrafish,these cells assume responsibility for spontaneous retinal regeneration,wherein endogenous Müller glia undergo proliferation,transform into Müller glia-derived progenitor cells,and subsequently regenerate the entire retina with restored ***,Müller glia in the mouse and human retina exhibit limited neural reprogramming.Müller glia reprogramming is thus a promising strategy for treating neurodegenerative ocular disorders.Müller glia reprogramming in mice has been accomplished with remarkable success,through various *** in molecular,genetic,epigenetic,morphological,and physiological evaluations have made it easier to document and investigate the Müller glia programming process in ***,there remain issues that hinder improving reprogramming efficiency and ***,understanding the reprogramming mechanism is crucial toward exploring factors that will improve Müller glia reprogramming efficiency,and for developing novel Müller glia reprogramming *** review describes recent progress in relatively successful Müller glia reprogramming *** also provides a basis for developing new Müller glia reprogramming strategies in mice,including epigenetic remodeling,metabolic modulation,immune regulation,chemical small-molecules regulation,extracellular matrix remodeling,and cell-cell fusion,to achieve Müller glia reprogramming in mice.

关键词： cell fusion chemical small-molecules epigenetic extracellular matrix immune metabolic mice Müller glia neurodegenerative diseases reprogramming retina regeneration