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Triply degenerate topological phase and stretchable Fermi arc surface states in gyromagnetic metamaterials

Physical Review B 2023年第3期108卷 035422-035422页

作者： Mingzhu Li Ning Han Lu Qi Liang Peng School of Information and Electrical Engineering Hangzhou City University Hangzhou 310015 China Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang ZJU-UIUC Institute Zhejiang University Hangzhou 310027 China School of Physical Science and Technology Yangzhou University Yangzhou 225002 China

Triple-fold band degeneracy (TBD) is an intriguing phase of topological semimetals which appears as the intermediate state between the four-folded degenerated Dirac points and the two-folded Weyl points. The resemblance of TBD in the photonics is interesting, because it indicates nonzero Berry curvature in momentum space and nontrivial topological property in real space. Recently, it was reported that TBD could be realized in the classical wave systems including phononic and photonic crystals. Unfortunately, those periodic structures can hardly provide a systematic strategy nor a compact layout in practical implementations. Hence, the resemblance of TBD is still a big challenge in topological photonics. In this work, we demonstrate that homogeneous gyromagnetic metamaterials (GMs) can be a good framework to stimulate the peculiar TBD. We discuss the emulation of triple degeneracy in dispersive GMs by carefully tuning the constitutive parameters. The introduction of nonlocality in the constitutive parameter of GMs provides the freedom of topology control of the GMs. Further, Fermi arc surface states are discussed and shown to be reflectionless against sharp corners. Remarkably, Fermi arc surface states, which occur at the boundary between the vacuum and the GMs, can be stretchable by tailoring the gap width of the GM's band structure. Our work provides a practical and flexible route to resemble TBD, which is of fundamental importance in designing reflectionless and unidirectional photonic topological devices.

关键词： Electron-cyclotron plasma waves Magneto-optics Surface states Topological effects in photonic systems Topological materials

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Synergistic Effect of Ag and Cu on Improving in Vitro Biological Properties of K2ti6o13 Nanowires for Potential Biomedical Applications

SSRN

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SSRN 2022年

作者： Lei, Shichang Qi, Yumin Zhao, Lichen Shen, Yutian An, Hailong Qu, Chang Wang, Xin Wang, Gaojiong Cui, Chunxiang Key Lab. for New Type of Functional Materials in Hebei Province School of Materials Science and Engineering Hebei University of Technology Tianjin300401 China Key Laboratory of Advanced Materials Ministry of Education Tsinghua University Beijing100084 China Key Laboratory of Molecular Biophysics Hebei Province Institute of Biophysics School of Health Sciences and Biomedical Engineering Hebei University of Technology Tianjin300401 China State Key Laboratory of Reliability and Intelligence of Electrical Equipment School of Electrical Engineering Hebei University of Technology Tianjin300130 China

The development of novel nanomaterials with synergistic biological effects has attracted extensive interest of the researchers. In the study, KTO with the doping amount of 0.5 mol% Ag and 0.5 mol% Cu (0.5 Ag-0.5 Cu-KTO) nanomaterial was successfully synthesized using two-step method of sol-gel and hydrothermal. The crystal structure of 0.5 Ag-0.5 Cu-KTO was still monoclinic KTO, Ag and Cu ions replacing partial Ti ions of KTO lattice. High specific surface area of 0.5 Ag-0.5 Cu-KTO (337.6 m 2 /g) provides more surface active sites for adsorption and Cu-Ag doping. More negative surface zeta potential (-32.83 mV in phosphate buffer solution (PBS) and -21.45 mV in physiological saline solution (PSS), respectively) would be beneficial to prevent the aggregation of the nanowires in physiological environment. Under the same doping amount, compared to single Cu doped KTO with the doping amount of 1.0 mol%, 0.5 Ag-0.5 Cu-KTO exhibited better antibacterial performance against gram-negative and gram-positive bacteria at only 100 μg/mL dose concentration, near to 1.0 mol% Ag doped KTO. And 0.5 Ag-0.5 Cu-KTO showed more excellent biocompatibility than 1.0 Ag-KTO, which was attribute to the introduction of Cu ions effectively decreasing the hemolytic and cytotoxic risks from Ag ions. As expected, the synthesized 0.5 Ag-0.5 Cu-KTO nanowires demonstrated excellent structural stability, high antibacterial activity, good hemocompatibility and cytocompatibility owing to the synergistic biological effects of Cu and Ag ions. 0.5 Ag-0.5 Cu-KTO nanowires will be a promising antimicrobial candidate for biomedical applications. © 2022, The Authors. All rights reserved.

关键词： Nanowires

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Sintering behavior and microwave dielectric properties of Ba1+x(Mg1/3Nb2/3)O3 ceramics

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2008年第8期30卷 27-29页

作者： Tian, Zhong-Qing Zhao, Wei-Lin Yu, Hong-Tao Chen, Wei-Ling School of Materials Science and Engineering Chongqing Institute of Technology Chongqing 400050 China State Key Lab. of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Sintering behavior, microstructure and microwave dielectric properties of Ba1+x(Mg1/3Nb2/3)O3 (-0.01 [less-than or equal to] x [less-than or equal to] 0.01) were investigated. An improvement of the degree of 1:2 ordering and sinterability was found in Ba-deficient Ba(Mg1/3 Nb2/3)O3 because there existed Ba vacancies. Excessive Ba inhibits the sintering and the degree of 1:2 ordering. It was proposed that excessive Ba exist in grain boundary and inhibit the movement of grain boundary. Therefore, the sintering was restrained. Ba-deficiency had little effect on dielectric constant of Ba(Mg1/3Nb2/3)O3 ceramics. With Ba-deficiency increasing, Qf value decreased drastically.

关键词： Ba(Mg1/3Nb2/3)O3 Microwave dielectric ceramic Ordering Sinterability

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Compact Low-Loss LTCC Diplexer Using Lumped-Element Lowpass and Bandpass Filters for 2.4/5-GHz Application

Compact Low-Loss LTCC Diplexer Using Lumped-Element Lowpass ...

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IEEE International Workshop on electromagnetics, Applications and Student Innovation (iWEM)

作者： Xulei Deng Jin-Xu Xu Xiu Yin Zhang Jingtao Zeng Kun Huang Shiwo Ta School of Electronic and Information Engineering South China University of Technology Guangzhou China State Key Laboratory of Analog and Mixed-Signal VLSI Institute of Microelectronics and FST-ECE University of Macau Macau China Pazhou Lab. Guangzhou China Guangdong Feng-hua Advanced Technology (Holding) Co. Ltd Zhaoqing China

ISBN: (纸本)9781665418294

This paper presents a low-temperature co-fired ceramic (LTCC) diplexer for 2.4/5-GHz applications. A simple schematic based on lumped-element lowpass and bandpass filters is proposed for realizing the diplexer. The lowpass filter is designed with a cut-off frequency of 3.7 GHz and three transmission zeros are generated to improve the out-of-band rejection. The bandpass filter is proposed with two transmission zeros locating at two sides of the passband. By using a complementary structure to combine the lowpass and bandpass filters, the LTCC diplexer is simulated with low insertion loss of smaller than 0.38 dB for 2.4 GHz application and 0.59-0.65 dB for 5-GHz application. The in-band isolation at the two operating bands are better than 20 dB, which is acceptable for many wireless applications. The presented LTCC diplexer has a circuit size is 1.0 × 0.5 × 0.35 mm 3 , which is very compact as compared to reported LTCC diplexers.

关键词： Band-pass filters Wireless communication Technological innovation Three-dimensional displays Conferences Cutoff frequency Insertion loss

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XRD and HRTEM analyses of the ball milled nanocrystalline FeNi alloy

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2006年第5期28卷 4-7页

作者： Wang, Wei Guan, Jian-Guo Wang, Qi Zhang, Qing-Jie State Key Lab. of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China School of Materials Science and Engineering University of Jinan Jinan 250022 China

The nanostructure of the ball milled FeNi particles were characterized as functions of the ball milling time (t) using quantitative X-ray diffraction (XRD), high resolution transmission electronic microscopy (HRTEM) analysis techniques. The results showed that the nanocrystalline bcc FeNi particles were availab.e using carbonyl iron and nickel powders as the raw materials during the high-energy ball milling. After 10 h ball milling, the alloy of carbonyl iron and carbonyl nickel began to form, and the sample kept its original bcc and fcc structure;after 100 h ball milling, the sample became a solid solution with bcc structure;after 200 h ball milling, the diffraction peak of Ni almost disappeared and the isotropic grains with Dmin achieved, which was mainly attributed to the dislocations of the nanocrystalline bcc FeNi suffering from severe plastic deformation by ball milling.

关键词： Alloy Carbonyl iron Carbonyl nickel High energy ball milling Nanocrystalline materials

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Resourceful Recovery of Wc@Co for Organic Pollutants Treatment Via Fenton-Like Reaction

SSRN

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SSRN 2023年

作者： Ding, Tao Zhu, Mengxiang Yan, Linghui Liu, Zhengyang Shi, Guosheng Zhou, Pin Yue, Dongting Shanghai Applied Radiation Institute State Key Lab. Advanced Special Steel Shanghai University NO.99 Shangda Road Baoshan District Shanghai200444 China Research Center of Secondary Resources and Environment Changzhou Institute of Technology Changzhou213032 China School of Environmental and Chemical Engineering

The unreasonable disposition of tungsten waste not only causes serious environmental contamination, but also leads to the metals resource wastage. A sustainable approach was proposed to obtain the Fenton-like catalyst derived from tungsten waste, which exhibits high efficiency for Peroxymonosulfate (PMS) activation. The recovered WC@Co, as a Fenton-like catalyst, was fabricated via thermal treatment of machining wet tungsten sludge, which induce the phase separation of Co and increases Co loading on WC. The formed Co0 as the electron-donor can not only facilitate the electron transform to W6+, but also active PMS for reactive species, thereby contributing to the enhanced generation of •SO4–, •OH, •O2−, and 1O2. Moreover, the high-valent Co(IV) was also generated in WC@Co/PMS system. These radical and nonradical pathways for reactive species make WC@Co/PMS system high oxidation capacity and stability for persistent organic pollutants degradation. Thus our proposed strategy has successfully realized recycling of metals such as W and Co for environmental remediation purposes. © 2023, The Authors. All rights reserved.

关键词： Catalysts

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Numerical simulation of natural caving method based on particle flow code in two dimensions

Beijing Keji Daxue Xuebao/Journal of University of Science a...

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Beijing Keji Daxue Xuebao/Journal of University of Science and technology Beijing 2007年第6期29卷 557-561页

作者： Wang, Lianqing Gao, Qian Wang, Jianguo Fang, Zulie State Key Lab. for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China Civil and Environmental Engineering School University of Science and Technology Beijing Beijing 100083 China

According to the theory and method of particle flow code in two dimensions (PFC2D), the block caving law of natural caving mining method was investigated. Based on the geologic conditions and the physical and mechanical properties of rock in a nickel-copper mine, the caving law in natural caving mining method was simulated by numerical method. The results show that the mechanical mechanism of natural caving method can be analyzed by PFC2D modeling, and the mining process of natural caving method is simulated effectively. The parameter variation of rockbody during the process of mining can be demonstrated easily. The initial caving radius of undercut in the mine is 10 m, and the continuous caving radius of undercut is 22 m. The numerical modeling is effective to guide the mining process of natural caving mining method in the mine.

关键词： Mining

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Diffusive nonreciprocity and thermal diode

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Physical Review B 2021年第1期103卷 014307-014307页

作者： Ying Li Jiaxin Li Minghong Qi Cheng-Wei Qiu Hongsheng Chen Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Zhejiang University Hangzhou 310027 China International Joint Innovation Center ZJU-UIUC Institute The Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

Wave propagation and diffusion in linear materials preserve local reciprocity in terms of a symmetric Green's function. For wave propagations, the relation between the fields entering and leaving a system is more relevant than the detailed information about the fields inside it. In such cases, the global reciprocity of the scattering off a system through several ports is more important, which is defined as the symmetric transmission between the scattering channels. When a two-port system supports nonreciprocal (electromagnetic, acoustic) wave propagation, it is a (optical, phonon) diode directly following the definition. However, to date no concrete definition or discussion has been made on the global reciprocity of diffusive processes through a multiple-port system. It thus remains unclear what are the differences and relations between the three concepts, namely, local nonreciprocity, global nonreciprocity, and diode effect in diffusion. Here, we provide theoretical analysis on the frequency-domain Green's function and define the global reciprocity of heat diffusion through a two-port system, which has a different setup from that of a thermal diode. We further prove the equivalence between a heat transfer system with broken steady-state global reciprocity and a thermal diode, assuming no temperature-dependent heat generation. The validities of some typical mechanisms in breaking the diffusive reciprocity and making a thermal diode have been discussed. Our results set a general background for future studies on symmetric and asymmetric diffusive processes.

关键词： Diffusion Heat transfer Metamaterials Diodes Green's function methods

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Bias voltage and properties of magnetron sputtered niobium films

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Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and technology 2008年第1期28卷 67-71页

作者： Cui, Jiangtao Tian, Xiubo Yang, Shiqin State Key Laboratory of Advanced Welding Production Technology School of Materials and Engineering Harbin Institute of Technology Harbin 150001 China Shenzhen Key Lab. of Composite Materials Shenzhen-Tech-Innovation International Shenzhen 518057 China

Niobium films were grown by DC magnetron sputtering on CrNi3Mo steel substrates. Its microstructures and mechanical properties were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and conventional probes. The results show that the negative bias voltages significantly affect its surface morphology and its mechanical properties. For example, at a bias of 150 V, the compact film has the highest erosion-resistance.

关键词： Magnetron sputtering

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OPTIMIZATION OF CONTROL PARAMETERS FOR PMSG-BASED WIND FARM AND SVG CONSIDERING SUBSYNCHRONOUS INTERACTION

OPTIMIZATION OF CONTROL PARAMETERS FOR PMSG-BASED WIND FARM ...

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International Conference on Renewable Power Generation

作者： Yuming Liu Biyue Huang Haishun Sun Yi Zhang Yingsheng Han Yongjun Yu State Key Lab of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China State Grid Xinjiang Electric Power Research Institute Urumqi 830011 Xinjiang Uygur Autonomous Region China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

Recently, sub-synchronous oscillations (SSO) phenomena have occurred in direct-drive permanent magnetic synchronous generator (D-PMSG) based wind farms. The majority of wind farms have installed the static var generator (SVG) to improve the voltage stability. But some oscillation events showed that SVG have produced adverse effect to the system. There are distinct subsynchronous interactions (SSI) between PMSG-based wind turbines and SVG. Researches have pointed out that when connected to a weak grid the improper control parameter is the main course of the SSI. Therefore, the control parameter of the system need be optimized considering the SSI problems. The mathematical model the analytical transfer function is derived firstly. Then the stable and feasible region of SVG's and PMSG's control parameter are determined according to stability criterion. At last, some coordination methods for the control parameters are proposed considering the SSI problems, and the electromagnetic simulations is carried out to verify the correctness and effectiveness.

关键词： RENEWABLE ENERGY PMSG SVG SUB-SYNCHRONOUS INTERACTION (SSI) PARAMETERS OPTIMIZATION

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