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Large unsaturated positive and negative magnetoresistance in Weyl semimetal TaP

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Science China(Physics,Mechanics & Astronomy) 2016年第5期59卷 21-26页

作者： JianHua Du HangDong Wang Qin Chen OianHui Mao Rajwali Khan BinJie XU yuxing zhou YanNan Zhang JinHu Yang Bin Chen ChunMu Feng MingHu Fang Department of Physics Zhejiang University Hangzhou 310027 China Department of Physics Hangzhou Normal University Hangzhou 310036 China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093 China

After successfully growing single-crystal TaP, we measured its longitudinal resistivity （Pxx） and Hall resistivity （Pyx） at magnetic fields up to 9 T in the temperature range of 2-300 K. At 8 T, the magnetoresistance （MR） reached 3.28 ×10^5% at 2 K, 176% at 300 K. Neither value appeared saturated. We confirmed that TaP is a hole-electron compensated semimetal with a low carrier concentration and high hole mobility ofμh=3.71 × 105 cm2/V s, and found that a magnetic-field-induced metal-insulator transition occurs at room temperature. Remarkably, because a magnetic field （H） was applied in parallel to the electric field （E）, a negative MR due to a chiral anomaly was observed and reached -3000% at 9 T without any sign of saturation, either, which is in contrast to other Weyl semimetals （WSMs）. The analysis of the Shubnikov-de Haas （SdH） oscillations superimposed on the MR revealed that a nontrivial Berry＇s phase with a strong offset of 0.3958, which is the characteristic feature of charge carriers enclosing a Weyl node. These results indicate that TaP is a promising candidate not only for revealing fundamental physics of the WSM state but also for some novel applications.

关键词： Weyl semimetal positive and negative magnetoresistance Weyl fermions

READING A PASSAGE TO INDIA FROM A POSTCOLONIAL PERSPECTIVE

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READING A PASSAGE TO INDIA FROM A POSTCOLONIAL PERSPECTIVE

作者： zhou yuxing 广东外语外贸大学

学位级别：硕士

A Passage to India has been the subject of a variety of interpretations since its publication. In current discussion of the novel, sexual and racial politics have replaced rhythm, romance, and irony as the dominant topics for consideration. Following this trend, and through application of posteolonial criticism to analysis of the novel, this paper focuses on the cross-cultural friendship in the book and analyzes how the author creates barriers for this theme in accordance with his description of India. The paper concentrates on three major colonial motifs that are found in this book as well as in other colonial literature: 1. misrepresentation of the Indian landscape 2. metaphysical and sexual horrors for Westerners in the colonized land 3. the feminine role imposed on the colonized group, and the repression and marginalization of females. The misrepresentation of India is reinforced by the distorted image of the Marabar Caves, and the different roles imposed on the colonizing and colonized group also serve to support the belief of Western superiority The thesis analyzes the way in which the novel develops the theme of Eurocentrism, and further argues that India should not unfairly be held responsible for the failure of cross-racial friendship.

关键词： Guangdong reserved

Superscalar communication: A runtime optimization for distributed applications

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Science China(Information Sciences) 2010年第10期53卷 1931-1946页

作者： LI HuiBa , LIU ShengYun, PENG yuxing, LI DongSheng, zhou HangJun & LU XiCheng National Laboratory for Parallel and Distributed Processing, National University of Defense Technology, Changsha 410073, China 1. National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

Building distributed applications is difficult mostly because of concurrency management. Existing approaches primarily include events and threads. Researchers and developers have been debating for decades to prove which is superior. Although the conclusion is far from obvious, this long debate clearly shows that neither of them is perfect. One of the problems is that they are both complex and error-prone. Both events and threads need the programmers to explicitly manage concurrencies, and we believe it is just the source of difficulties. In this paper, we propose a novel approach—superscalar communication, in which concurrencies are automatically managed by the runtime system. It dynamically analyzes the programs to discover potential concurrency opportunities; and it dynamically schedules the communication and the computation tasks, resulting in automatic concurrent execution. This approach is inspired by the idea of superscalar technology in modern microprocessors, which dynamically exploits instruction-level parallelism. However, hardware superscalar algorithms do not fit software in many aspects, thus we have to design a new scheme completely from scratch. Superscalar communication is a runtime extension with no modification to the language, compiler or byte code, so it is good at backward compatibility. Superscalar communication is likely to begin a brand new research area in systems software, which is characterized by dynamic optimization for networking programs.

关键词： network programming concurrency event thread superscalar

Magnetoresistance and Kondo Effect in Nodal-Line Semimetal VAs_(2)

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Chinese Physics Letters 2021年第1期38卷 92-98页

作者： Shuijin Chen Zhefeng Lou yuxing zhou Qin Chen Binjie Xu Chunxiang Wu Jianhua Du Jinhu Yang Hangdong Wang Minghu Fang Department of Physics Zhejiang UniversityHangzhou 310027China Department of Applied Physics China Jiliang UniversityHangzhou 310018China Department of Physics Hangzhou Normal UniversityHangzhou 310036China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

We performed calculations of the electronic band structure and the Fermi surface,measured the longitudinal resistivity ρxx(T,H),Hall resistivity ρxy(T,H),and magnetic susceptibility as a function of temperature at various magnetic fields for VAs_(2) with a monoclinic crystal *** band structure calculations show that VAs_(2) is a nodal-line semimetal when spin-orbit coupling is *** emergence of a minimum at around11 K in ρxx(T) measured at H=0 demonstrates that some additional magnetic impurities(V^(4+),S=1/2)exist in VAs_(2) single crystals,inducing Kondo scattering,evidenced by both the fitting of ρxx(T) data and the susceptibility *** is found that a large positive magnetoresistance(MR) reaching 649% at 10 K and 9 T,its nearly quadratic field dependence,and a field-induced up-turn behavior of ρxx(T) also emerge in VAs_(2),although MR is not so large due to the existence of additional scattering compared with other topological nontrivial/trivial *** observed properties are attributed to a perfect charge-carrier compensation,which is evidenced by both the calculations relying on the Fermi surface and the Hall resistivity *** results indicate that the compounds containing V(3d^(3)4s^(2)) element can be as a platform for studying the influence of magnetic impurities to the topological properties.

关键词： resistance Kondo resistivity

Quantum critical behavior in an antiferromagnetic heavy-fermion Kondo lattice system(Ce(1-x)Lax)2Ir3Ge5

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Chinese Physics B 2017年第1期26卷 438-443页

作者： Rajwali Khan Qianhui Mao Hangdong Wang Jinhu Yang Jianhua Du Binjie Xu yuxing zhou Yannan Zhang Bing Chen Minghu Fang Department of Physics Zhejiang University Hangzhou 310027 China Department of Physics Hangzhou Normal University Hangzhou 310036 China Collaborative Innovation Center of Advanced Microstructures Nanfing 210093 China

The measurements on temperature dependences of magnetic susceptibility χ（T）, specific heat C（T）, and electrical resistivity ρ（T） were carried out for the antiferromagnetic（AFM）（Ce（1-x）Lax）2Ir3Ge5（0 ≤ x ≤ 0.66） system. It was found that the Neel temperature TNdecreases with increasing La content x, and reaches 0 K near a critical content xcr =0.6. A new phase diagram was constructed based on these measurements. A non-Fermi liquid behavior in ρ（T） and a log T relationship in C（T） were found in the samples near xcr, indicating them to be near an AFM quantum critical point（QCP） with strong spin fluctuation. Our finding indicates that（Ce（1-x）Lax）2Ir3Ge5 may be a new platform to search for unconventional superconductivity.

关键词： quantum critical point antiferromagnetic Kondo lattice system (Ce1-xLax)2Ir3Ge5

Effects of electro-acupuncture on brain tissue norepinephrine contents in a morphine withdrawal anxiety mouse model

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Neural Regeneration Research 2008年第4期3卷 402-405页

作者： Qizhi zhou yuxing Liu Xuguang Liu Jiaolu Wei Yong Tang Junmei Wu Yi Pu Acupuncture ＆ Tuina College Chengdu University of Traditional Chinese Medicine Chengdu 610075 Sichuan Province China

BACKGROUND： Following morphine withdrawal, anxiety is associated with abnormal norepinephrine content change. However, increasing blood lactic acid content can induce anxiety or panic in patients with anxiety disorder or endogenous opioid peptide functional disorder. OBJECTIVE： This study was designed to observe the effects of electro-acupuncture, at the ＂Sanyinjiao＂ point （SP 6）, on brain tissue norepinephrine and blood lactic acid content in anxiety-model mice after morphine withdrawal. DESIGN： A randomized controlled animal experiment. SETTING： This study was performed in the Laboratory of Acupuncture, Electro-acupuncture ＆ Tuina College, Chengdu University of Traditional Chinese Medicine, from June to September 2001. MATERIALS： A total of 50 healthy Kunming male mice were provided by the Laboratory Animal Center of Chengdu University of Traditional Chinese Medicine. The protocol was performed in accordance with ethical guidelines stated in the Guide for the use and care of laboratory animals, approved by the Committee on the Care and Use of Laboratory Animals of the Institute of Laboratory Animal Resources Commission on Life Sciences, National Research Council, China （1985）. Experimental reagents and equipment used were as follows： morphine hydrochloride （Lot No. 930503, Shenyang No.1 Pharmaceutical Factory, China）, norepinephrine （Sigma Chemical Company, USA）, fluorospectrophotometer （RF-510, Shimadzu Corporation, Japan）, Han electro-acupuncture apparatus （WQ 1002, No. zun （91）-227270-588, Beijing Anlong Photoelectricity-Technique Company, China）, and T-maze （self-made）. METHODS： A total of 50 mice were randomly divided into 5 groups, with 10 mice in each group： blank control, T-maze, model, model ＋ electro-acupuncture, and electro-acupuncture groups. Establishment of anxiety model after morphine withdrawal： the mouse hot plate assay was used to detect the activity of morphine. The median effective dose of morphine, 2.95 mg/kg, was defined as the base. Mice wer

关键词： morphine withdrawal anxiety norepinephrine lactic acid acupuncture

Large Magnetoresistance and Nontrivial Berry Phase in Nb_(3)Sb Crystals with A15 Structure

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Chinese Physics Letters 2021年第8期38卷 110-114页

作者： Qin Chen yuxing zhou Binjie Xu Zhefeng Lou Huancheng Chen Shuijin Chen Chunxiang Wu Jianhua Du Hangdong Wang Jinhu Yang Minghu Fang Department of Physics Zhejiang UniversityHangzhou 310027China Department of Applied Physics China Jiliang UniversityHangzhou 310018China Department of Physics Hangzhou Normal UniversityHangzhou 310036China Collaborative Innovation Center of Advanced Microstructure Nanjing UniversityNanjing 210093China

Compounds with the A15 structure have attracted extensive attention due to their superconductivity and nontrivial topological band *** have successfully grown Nb_(3)Sb single crystals with the A15 structure and systematically measured the longitudinal resistivity,Hall resistivity and quantum oscillations in *** to other topological trivial/nontrivial semimetals,Nb_(3)Sb exhibits large magnetoresistance(MR)at low temperatures(717%,2 K and 9 T),unsaturating quadratic field dependence of MR and up-turn behavior in ρ_(xx)(T)curves under magnetic field,which is considered to result from a perfect hole-electron compensation,as evidenced by the Hall resistivity *** nonzero Berry phase obtained from the de-Hass van Alphen(dHvA)oscillations demonstrates that Nb_(3)Sb is topologically *** results indicate that Nb_(3)Sb superconductor is also a semimetal with large MR and nontrivial Berry *** indicates that Nb_(3)Sb may be another platform to search for the Majorana zero-energy mode.

关键词： nontrivial Berry topological

空间污染条件下红外测量相机响应衰减模型的建立与应用

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光学学报 2015年第2期35卷 187-193页

作者：张寅丛明煜周宇星哈尔滨工业大学空间光学工程研究中心黑龙江哈尔滨150001

基于某型号大气辐射测量卫星在轨定标实验数据,开展了空间污染物对天基红外测量相机响应性能的影响研究。建立了具有明确物理意义的测量相机灰度响应衰减模型,使用实测数据对模型参数进行了拟合,拟合相对均方根误差小于1%,参数值与其物... 详细信息

基于某型号大气辐射测量卫星在轨定标实验数据,开展了空间污染物对天基红外测量相机响应性能的影响研究。建立了具有明确物理意义的测量相机灰度响应衰减模型,使用实测数据对模型参数进行了拟合,拟合相对均方根误差小于1%,参数值与其物理意义吻合较好;提出了基于相机线性响应范围与最小辐射分辨率要求双重约束下的空间污染容限确定准则,得出了推荐去污间隔时间为1250 h的结论;给出了利用衰减模型预估任意时刻定标系数的方法,分别利用模型预估定标系数、历史定标系数以及当轨定标系数对测量灰度数据进行了辐射标定,预估定标系数的标定误差小于3%,能够在保证像面质量的同时提高测量精度。

关键词：遥感相机响应衰减模型在轨辐射定标空间污染物污染容限

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高铁基硅混凝剂形成铅絮体的分形维数分析

中国石油大学学报（自然科学版） 2014年第4期38卷 186-191页

作者：于衍真孙勇谭娟程磊周玉兴济南大学土木建筑学院山东济南250022

利用高铁基硅混凝剂及聚磷硫酸铁(PPFS)对含铅工业废水进行处理,考察含铅工业废水处理过程中分形维数对铅絮体的影响以及与铅离子去除率的关系。结果表明:对于模拟的含铅工业废水,高铁基硅混凝剂的最佳投药量(体积分数)为3.5×10-3,最佳... 详细信息

利用高铁基硅混凝剂及聚磷硫酸铁(PPFS)对含铅工业废水进行处理,考察含铅工业废水处理过程中分形维数对铅絮体的影响以及与铅离子去除率的关系。结果表明:对于模拟的含铅工业废水,高铁基硅混凝剂的最佳投药量(体积分数)为3.5×10-3,最佳的pH值为9.5,在此最佳条件下,铅絮体的分形维数最大,铅絮体最为密实,铅离子的去除率也最高,分形维数与铅离子去除率之间有良好的相关性;对于实际含铅工业废水,高铁基硅混凝剂的最佳投量为8×10-3,除率为92.5%,效果要好于PPFS;两种混凝剂的分形维数与铅离子去除率之间同样有良好相关性。

关键词：高铁基硅混凝剂分形理论絮体分形维数