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Electronic structure of correlated topological insulator candidate YbB6 studied by photoemission and quantum oscillation

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Chinese Physics B 2020年第1期29卷 70-75页

作者： T zhang G Li S C Sun N Qin L kang S H Yao H M Weng S k Mo L Li z k liu L X Yang Y L Chen State key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Department of Physics University of MichiganAnn ArborMI 48109USA Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China National Laboratory of Solid State Microstructures&Department of Materials Science and Engineering Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Quantum Matter BeijingChina Songshan Lake Materials Laboratory Dongguan 523808China CAS Center for Excellence in Topological Quantum Computation Beijing 100190China Physical Science Laboratory Huairou National Comprehensive Science CenterBeijing 101400China Advanced Light Source Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA School of Physical Science and Technology ShanghaiTech University and CAS-Shanghai Science Research CenterShanghai 201210China ShanghaiTech Laboratory for Topological Physics Shanghai 200031China Frontier Science Center for Quantum Information Beijing 100084China Department of Physics Clarendon LaboratoryUniversity of Oxford Parks RoadOxford OX13PUUK

Angle-resolved photoemission spectroscopy(ARPES)and torque magnetometry(TM)measurements have been carried out to study the electronic structures of a correlated topological insulator(TI)candidate Yb *** observed clear surface states on the[001]surface centered at theГ^- and М^- points of the surface Brillouin ***,the fermiology revealed by the quantum oscillation of TM measurements agrees excellently with ARPES ***,the band structures we observed suggest that the band inversion in Yb B6 happens between the Yb5 dand B2bands,instead of the Yb5dand Yb4fbands as suggested by previous theoretical investigation,which will help settle the heavy debate regarding the topological nature of samarium/ytterbium hexaborides.

关键词： topological insulator electronic structure surface states

A Fourier Spectral Moving Mesh Method for the Cahn-Hilliard Equation with Elasticity

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Communications in Computational Physics 2009年第2期5卷 582-599页

作者： W.M.Feng P.Yu S.Y.Hu z.k.liu Q.Du L.Q.Chen Department of Materials Science and Engineering Pennsylvania State UniversityUniversity ParkPA 16802USA Department of Mathematics Pennsylvania State UniversityUniversity ParkPA 16802USA Pacific Northwest National Laboratory RichlandWA 99354USA

In recent years,Fourier spectral methods have emerged as competitive numerical methods for large-scale phase field simulations of microstructures in computational materials *** further improve their effectiveness,we recently developed a new adaptive Fourier-spectral semi-implicit method(AFSIM)for solving the phase field equation by combining an adaptive moving mesh method and the semi-implicit Fourier spectral *** this paper,we present the application of AFSIM to the Cahn-Hilliard equation with inhomogeneous,anisotropic *** implementations and test examples in both two and three dimensions are considered with a particular illustration using the well-studied example of mis-fitting particles in a solid as they approach to their equilibrium *** is shown that significant savings in memory and computational time is achieved while accurate solutions are preserved.

关键词： Phase field diffuse interface moving mesh adaptive mesh Fourier-spectral method adaptive spectral method Cahn-Hilliard equation elasticity

Monte Carlo simulation of mirror magnetic field effects in a helium direct current gas discharge

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Monte Carlo simulation of mirror magnetic field effects in a...

作者： Y H liu, z L liu, k L Yao, H X liu and J z Wang Department of Physics, Huazhong University of Science and Technology and the National Laboratory of Laser Technology. Wuhan 430074, People’s Republic of China

Using the Monte Carlo method, we study the behaviour of electrons as they move under the influence of a mirror magnetic field and a uniform electric field in positive column of a helium dc gas discharge. The symmetrical axis of the mirror magnetic fields is in a direction parallel to the uniform electric field. Some types of collisions (elastic, excitation and ionization collision) ate considered. Graphs showing the electron density and the energy distributions, the angular and the energy distributions at the end of the positive column, and the percentage of electrons that reach the wall and the end of the positive column are presented. The results indicate that the mirror magnetic field can control the electron transport behaviour in the positive column. In the presence of the mirror magnetic field the electrons are restricted in the middle pan of the positive column and the electron energy is reduced;the electron scattering angles are extended by the mirror magnetic fields. These results are in good agreement with experimental results.

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应用光谱测量牙周病炎性指标

口腔医学研究 2013年第6期29卷 538-542页

作者：张春阳范春孟冬梅肖喜梅 k.-z liu 向晓明青岛大学医学院附属医院口腔科山东青岛266003 加拿大国家科学院生物诊断研究所

目的:应用光谱测量局部组织的水肿和血流动力学变化,评价光学光谱在不同人群中对牙周组织多种炎性指标(组织的氧合作用、组织的总血红蛋白量、脱氧血红蛋白、含氧血红蛋白和组织水肿)的评估能力。方法:使用手提式的近红外光谱测量仪分... 详细信息

目的:应用光谱测量局部组织的水肿和血流动力学变化,评价光学光谱在不同人群中对牙周组织多种炎性指标(组织的氧合作用、组织的总血红蛋白量、脱氧血红蛋白、含氧血红蛋白和组织水肿)的评估能力。方法:使用手提式的近红外光谱测量仪分别从健康组织区域(n=54)、牙龈炎区域(n=50)、牙周炎区域(n=26)获取光谱并对其进行处理及评估。使用非参数的散射损失函数的改良比尔-兰伯特分解方式来研究每一种炎性组分在整体光谱中的相对分布。结果:光学光谱成功地用于评估牙周组织中复杂的炎症环境。数字表明牙周炎组织的氧合作用与牙龈炎区域及健康组织区相比明显降低(P<0.05)。这主要是由于在牙周炎区域的脱氧血红蛋白含量比牙龈炎区域(P=0.05)及健康组织区(P<0.01)明显增加所造成的。组织的含水量没有统计学差异,但是当牙周炎区域与牙龈炎区域及健康组织区域相比时,水指数相关的组织电解质水平及温度仍有统计学差异(P<0.03)。结论:本项研究进一步证实光学光谱能够在人类牙周组织中直接测量炎性指标。近红外线可见光谱可作为一种简单的、低耗的、无创伤、椅旁的、定位精确的诊断工具用于牙周病的诊断。

关键词：近红外光谱水肿炎症牙周炎组织氧合状态

基于背景噪声的龙门山断裂带10年地震波速变化研究

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世界地震译丛 2020年第2期51卷 185-203页

作者： z.k.liu J.L.Huang P.He J.J.Qi 齐娟娟中国地质大学(北京)

本研究利用龙门山断裂带附近20个宽频带地震台站2007~2017年10年期间的连续波形资料,通过三分量地震背景噪声干涉测量技术,得到了4个不同周期的相对地震波速变化,重点研究了2008年汶川M W7.9地震和2013年芦山M W6.6地震对波速变化的影... 详细信息

本研究利用龙门山断裂带附近20个宽频带地震台站2007~2017年10年期间的连续波形资料,通过三分量地震背景噪声干涉测量技术,得到了4个不同周期的相对地震波速变化,重点研究了2008年汶川M W7.9地震和2013年芦山M W6.6地震对波速变化的影响。结果显示,在1~3s和3~8s周期,汶川地震均造成了断层区附近急剧的同震波速降低,降幅在0.04%~0.06%之间;在地震发生后的9年,波速的恢复幅度仅为同震波速降低值的1/4,即约3/4的波速降低未得到恢复。对于6~15s周期,我们观测到在汶川主震后约100天时出现了微小的波速下降,降幅约为0.0066%。本研究还发现芦山地震造成了1~3s周期的微小但较为可靠的波速降低,幅度约为0.01%。我们推断波速变化的物理机制可能包括:地震导致的浅层地壳(小于3km)破坏、断层区深部(约10km)的介质破坏,以及断裂带深部(约20km)的震后余滑。汶川地震后龙门山断裂区域波速恢复非常缓慢,这可能是由于区域应力加载速率较慢使得龙门山断裂带在汶川震后的缓慢愈合导致的。

关键词：地震背景噪声地震波速变化汶川地震芦山地震龙门山断裂带地震波速震后恢复

[Mid-long term follow-up reports on head and neck rhabdomyosarcoma in children]

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zhonghua er ke za zhi = Chinese journal of pediatrics 2024年第1期63卷 62-69页

作者： C Duan S D He S C Wang M Jin W zhao X S Wang z k liu T Yu L J He X M Wang C Y Cui X Ni Y Su Department of Medical Oncology Pediatric Oncology CenterBeijing Children's Hospital Capital Medical University National Center for Children's Health National Key Clinical Discipline of Pediatric Oncology Laboratory for Clinical Medicine Capital Medical University Key Laboratory of Major Diseases in Children Ministry of Education Beijing100045 China. Department of Otorhinolaryngology Head and Neck Surgery Beijing Children's Hospital Capital Medical University National Center for Children's Health Beijing100045 China. Department of Radiation Oncology Peking Union Medical College Hospital Peking Union Medical College Chinese Academy of Medical Sciences Beijing100730 China. Medical Imaging Center Beijing Children's Hospital Capital Medical University National Center for Children's Health Beijing100045 China. Department of Pathology Beijing Children's Hospital Capital Medical UniversityNational Center for Children's Health Beijing100045 China. Department of Ultrasound Beijing Children's Hospital Capital Medical UniversityNational Center for Children's Health Beijing100045 China. School of Pharmaceutical Sciences Capital Medical University Laboratory for Clinical Medicine Capital Medical University Beijing100069 China.

To analyze the clinical characteristics of children with head and neck rhabdomyosarcoma (RMS) and to summarize the mid-long term efficacy of Beijing Children's Hospital Rhabdomyosarcoma 2006 (BCH-RMS-2006) regimen and China Children's Cancer Group Rhabdomyosarcoma 2016 (CCCG-RMS-2016) regimen. A retrospective cohort study. Clinical data of 137 children with newly diagnosed head and neck RMS at Beijing Children's Hospital, Capital Medical University from March 2013 to December 2021 were collected. Clinical characteristic of patients at disease onset and the therapeutic effects of patients treated with the BCH-RMS-2006 and CCCG-RMS-2016 regimens were compared. The treatments and outcomes of patients with recurrence were also summarized. Survival analysis was performed by kaplan-Meier method, and Log-Rank test was used for comparison of survival rates between groups. Among 137 patients, there were 80 males (58.4%) and 57 females (41.6%), the age of disease onset was 59 (34, 97) months. The primary site in the orbital, non-orbital non-parameningeal, and parameningeal area were 10 (7.3%), 47 (34.3%), and 80 (58.4%), respectively. Of all patients, 32 cases (23.4%) were treated with the BCH-RMS-2006 regimen and 105 (76.6%) cases were treated with the CCCG-RMS-2016 regimen. The follow-up time for the whole patients was 46 (20, 72) months, and the 5-year progression free survival (PFS) and overall survival (OS) rates for the whole children were (60.4±4.4)% and (69.3±4.0)%, respectively. The 5-year OS rate was higher in the CCCG-RMS-2016 group than in BCH-RMS-2006 group ((73.0±4.5)% (56.6±4.4)%, =4.57,=0.029). For the parameningeal group, the 5-year OS rate was higher in the CCCG-RMS-2016 group (61 cases) than in BCH-RMS-2006 group (19 cases) ((57.3±7.6)% (32.7±11.8)%, =4.64,=0.031). For the group with meningeal invasion risk factors, the 5-year OS rate was higher in the CCCG-RMS-2016 group (54 cases) than in BCH-RMS-2006 group (15 cases) ((57.7±7.7)% (30.0±12.3)%, =4.76

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Spectral measurements of hypervelocity flow in an expansion tunnel

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Acta Mechanica Sinica 2019年第1期35卷 24-31,I0002页

作者： C.k.Yuan k.zhou Y.F.liu z.M.Hu z.L.Jiang State key Laboratory of High-Temperature Gas Dynamic Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences. University of Chinese Academy of Sciences Beijing 100049China China Academy of Aerospace Aerodynamics Beijing 100074China

Atmospheric reentry vehicles and planetary probes fly through the atmosphere at hypervelocity speed. At such speed, there is a significant proportion of heat load to the vehicle surface due to radiative heating. Accurate prediction needs a good knowledge of the radiation spectrum properties. In this paper, a high-speed camera and spectrograph coupled to an intensified charge-coupled device have bee n impleme nted to inv estigate the rad i at io n flow over a semi-cylinder model. The experiments were carried out in the JF16 expansi on timnel with secondary shock velocity of 7.9 km·s^-1. Results show that the emissio n spectrum comprises several atomic lines and molecular band systems. We give detailed data of the radiation spectrum, shock shape, shock detached distance and radiation intensity varying with space and wavelength. This valuable experimental dataset will be helpful to validate computational fluid dynamics codes and radiation models, which equates to increased prediction accuracy of radiation heating. Also, some suggestions for spectral measurement in hypervelocity flow field were list in the end.

关键词： Spectral measurement Hypervelocity flow Radiation Expansion tunnel

A review on MBE-grown HgCdSe infrared materials on GaSb(211)B substrates

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Chinese Physics B 2019年第1期28卷 116-125页

作者： z k zhang W W Pan J L liu W Lei Department of Electrical Electronic and Computer EngineeringThe University of Western Australia35 Stirling HighwayCrawley 6009Australia

We review our recent efforts on developing HgCdSe infrared materials on Ga Sb substrates via molecular beam epitaxy(MBE) for fabricating next generation infrared detectors with features of lower production cost and larger focal plane array format size. In order to achieve high-quality HgCdSe epilayers, znTe buffer layers are grown before growing HgCdSe, and the study of misfit strain in znTe buffer layers shows that the thickness of znTe buffer layer needs to be below 300 nm in order to minimize the generation of misfit dislocations. The cut-off wavelength/alloy composition of HgCdSe materials can be varied in a wide range by varying the ratio of Se/Cd beam equivalent pressure during the HgCdSe *** temperature presents significant impact on the material quality of HgCdSe, and lower growth temperature leads to higher material quality for HgCdSe. Typically, long-wave infrared HgCdSe(x = 0.18, cut-off wavelength of 10.4 μm at 80 k) presents an electron mobility as high as 1.3×10~5cm^2·V^(-1)·s^(-1), a background electron concentration as low as 1.6×10^(16)cm^(-3), and a minority carrier lifetime as long as 2.2 μs. These values of electron mobility and minority carrier lifetime represent a significant improvement on previous studies of MBE-grown HgCdSe reported in the open literatures,and are comparable to those of counterpart HgCdTe materials grown on lattice-matched CdznTe substrates. These results indicate that HgCdSe grown at the University of Western Australia, especially long-wave infrared can meet the basic material quality requirements for making high performance infrared detectors although further effort is required to control the background electron concentration to below 10^(15)cm^(-3). More importantly, even higher quality HgCdSe materials on GaSb are expected by further optimizing the growth conditions, using higher purity Se source material, and implementing postgrowth thermal annealing and defect/impurity gettering/filtering. Our results demonst

关键词： infrared detector HgCdSe GaSb molecular beam epitaxy

Synthesis of Single-Crystal TiO_2 Nanowire Using Titanium Monoxide Powder by Thermal Evaporation

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Journal of Materials Science & Technology 2012年第5期28卷 385-390页

作者： z.G.Shang z.Q.liu P.J.Shang J.k.Shang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

TiO 2 nanowires were synthesized successfully in a large quantity by thermal evaporation using titanium monoxide powder as precursor. X-ray diffraction results showed that all the products were pure rutile phase of TiO 2 . According to microstructural observations, the nanowires have two typical morphologies, a long straight type and a short tortuous type. The straight nanowires were obtained at a wide temperature range of 900–1050 ℃, while the tortuous ones were formed below 900 ℃. Transmission electron microscopy characterization revealed that both the straight and the tortuous nanowires are single-crystal rutile TiO 2 . The preferential growth direction of the nanowires was determined as [110] orientation according to electron diffraction and high-resolution image analyses. The morphological change of TiO 2 nanowires was discussed by considering the different atomic diffusion rates of Ti atoms caused by the phase transformation in Ti substrate at around 900 ℃.

关键词： Rutile-TiO 2 Alloy nanowires Transmission electron microscopy (TEM) characterization Crystal structure identification Growth mechanism Thermal evaporation