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Broadband strong optical dichroism in topological Dirac semimetals with Fermi velocity anisotropy

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Chinese Physics B 2020年第7期29卷 128-134页

作者： j Lim K j A Ooi C Zhang L K ang Yee Sin ang Science Math and TechnologySingapore University of Technology and DesignSingapore School of Energy and Chemical Engineering Xiamen University MalaysiaSelangor Darul Ehsan 43900Malaysia College of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361005China School of Physics University of WollongongNorthfields AvenueNew South Wales 2522Australia

Prototypical three-dimensional(3D)topological Dirac semimetals(DSMs),such as Cd3As2 and Na3Bi,contain electrons that obey a linear momentum-energy dispersion with different Fermi velocities along the three orthogonal momentum *** being extensively studied in recent years,the inherent Fermi velocity anisotropy has often been neglected in the theoretical and numerical studies of 3D *** this omission does not qualitatively alter the physics of light-driven massless quasiparticles in 3D DSMs,it does quantitatively change the optical coefficients which can lead to nontrivial implications in terms of nanophotonics and plasmonics *** we study the linear optical response of 3D DSMs for general Fermi velocity values along each *** the signature conductivity-frequency scaling,σ(ω)∝ω,of 3D Dirac fermion is well-protected from the Fermi velocity anisotropy,the linear optical response exhibits strong linear dichroism as captured by the universal extinction ratio scaling law,Λi j=(vi/v j)^2(where i=j denotes the three spatial coordinates x,y,z,and vi is the i-direction Fermi velocity),which is independent of frequency,temperature,doping,and carrier scattering *** Cd3As2 and Na3Bi3,an exceptionally strong extinction ratio larger than 15 and covering a broad terahertz window is *** findings shed new light on the role of Fermi velocity anisotropy in the optical response of Dirac semimetals and open up novel polarization-sensitive functionalities,such as photodetection and light modulation.

关键词： topological Dirac semimetal optical anisotropy linear dichroismn linear response theory

Constructing a stable cobalt-nitrogen-carbon air cathode from coordinatively unsaturated zeolitic-imidazole frameworks for rechargeable zinc-air batteries

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Nano Research 2022年第7期15卷 5895-5901页

作者： Tingting wang Meng Liu Somboon Chaemchuen jichao wang Ye Yuan Cheng Chen ang Qiao Francis Verpoort Zongkui Kou State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Zeolitic-imidazole frameworks(ZIFs)derivations have widely emerged as an efficient air cathode of zinc-air batteries(ZABs)due to excellent bifunctional oxygen electrocatalysis ***,they are not stable enough for long-term operation of rechargeable ZABs because of weak association with current collector,especially under bending conditions for flexible ZAB ***,we show that by purposely designing coordinatively unsaturated ZIFs via a facile morphology regulation,which can be chemically linked on acid-treated carbon cloth,a stable Co-N-C air cathode is therefore derived where Co nanoparticles(NPs)are uniformly confined within the Co-N-C matrix on carbon cloth(Co/Co-N-C/CC).Specifically,when without being stabilized from carbon cloth,the pyrolysis of ZIFs with different unsaturated coordination levels has a negligible impact on the bifunctional oxygen-catalyzed *** optimal Co/Co-N-C/CC catalyst assembled ZAB possesses a large open circuit voltage of 1.415 V and a high peak power density of 163 mW·cm^(−2) as well as excellent cycling durability upon 630 discharge–charge cycles with 61%voltage efficiency remained,largely exceeding those of a benchmark Pt/C-IrO_(2) catalyst assembled *** synergy between Co NPs and active Co-N-C sites via electronic interaction induces the outstanding bifunctional oxygen-catalyzed activity and cathode *** present work highlights the importance of unsaturated coordination structures in ZIFs precursors for the performance of derived nanostructures in integrated electrodes.

关键词： coordinatively unsaturated zeolitic-imidazole frameworks(ZIFs) cobalt-nitrogen-carbon bifunctional air electrodes zincair battery flexible electrode

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基于宽度自编码网络的单分类集成算法

信号处理 2024年第4期40卷 776-788页

作者：施一帆陈宇昂曾焕强杨楷翔华侨大学工学院福建泉州362021 华南理工大学计算机科学与工程学院广东广州510006 计算机软件新技术国家重点实验室江苏南京210023

异常检测是模式识别领域的经典研究,然而在极端类别不平衡场景下,异常样本匮乏,训练数据仅包含正常样本,传统异常检测方法难以适用。因此,单分类算法逐渐受到关注,它只使用目标类样本构建决策边界,实现对非目标类样本的识别。目前单分... 详细信息

异常检测是模式识别领域的经典研究,然而在极端类别不平衡场景下,异常样本匮乏,训练数据仅包含正常样本,传统异常检测方法难以适用。因此,单分类算法逐渐受到关注,它只使用目标类样本构建决策边界,实现对非目标类样本的识别。目前单分类算法已经取得了显著进展,然而也存在一些局限性:(1)原始特征空间容易受噪声特征干扰;(2)单模型的单分类算法难以从多个特征空间学习更全面的决策边界;(3)缺少对先前模型的欠拟合样本进行针对性学习。为了解决这些问题,本文提出了基于宽度自编码网络的单分类集成算法(Ensemble One-class Classification Based on BLS-Autoencoder,EOC-BLSAE)。首先,本文设计了一种单分类宽度自编码网络模型(One-class BLS-Autoencoder,OC-BLSAE),它能高效学习原始特征空间到重构特征空间的非线性映射关系,利用重构误差构建决策边界;接着,本文设计了单分类Boosting策略,通过最小化全局重构损失,迭代学习欠拟合样本,从而多角度构建OC-BLSAE模型,并自适应评估模型的可靠性;最终,加权集成多个OC-BLSAE模型,有效提升整体算法准确性和鲁棒性。在实验中,本文在16个不同规模的单分类任务上进行参数实验、对比实验和消融实验,结果表明所提算法参数选择较为灵活,算法各模块能够相互协同,有效提升单分类任务的准确性和鲁棒性,整体性能超过前沿单分类方法。

关键词：单分类异常检测宽度学习系统集成学习

Motion direction prediction through spike timing based on micro Capsnet networks

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Science China(Technological Sciences) 2022年第11期65卷 2763-2775页

作者： ZHang HuaLiang LIU ji wang BaoZeng DAI jun LIAN jinLing KE ang ZHAO YuWei ZHOU jin wang ChangYong Bejing Institute of Basic Medical Sciences Bejing 100850China School of Artificial Intlligence and Automation Huazhong University of Science and TechnologyWuhan 430074China

Neural activity extraction and neural decoding from neural signals are an important part of critical components of brain-computer interface *** the development of brain-computer interface technology,the demand for precise external control and nervous activities in macaque monkey during unilateral hand grasp has increased the complexity of control and neural decoding,which puts forward higher requirements for the accuracy and stability of feature extraction and neural *** this study,a micro Capsnet network architecture that consists of a few network layers,a vector feature structure,and optimization network parameters,is proposed to decrease the computing time and complexity,decrease artificial debugging,and improve the decoding *** with KNN,SVM,XGBOOST,CNN,Simple RNN,and LSTM,the algorithm in this study improves the decoding accuracy by 98.03%,and achieves state-of-the-art accuracy and stronger ***,the proposed algorithm can further enhance the control accuracy in the brain-computer interface.

关键词： spike timing micro Capsnet network brain-computer interface motion direction prediction optimized network parameter

Drought fluctuations based on dendrochronology since 1786 for the Lenglongling Mountains at the northwestern fringe of the East Asian summer monsoon region

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journal of Arid Land 2016年第4期8卷 492-505页

作者： HOU Ying NIU Zhenmin ZHENG Fang wang Nai'ang wang jianyu LI Zhuolun CHEN Hongxiang ZHang Xuemin College of Earth and Environmental Sciences Ningxia University Center for Climate Change and Hydrologic Cycle in Arid Region College of Earth and Environmental ScienceLanzhou University

The Lenglongling Mountains （LLM） located in northeastern part of the Tibet Plateau, belong to a marginal area of the East Asian summer monsoon （EASM） and are sensitive to monsoon dynamics. Two tree-ring width chronologies developed from six sites of Picea crassifolia in the LLM were employed to study the regional drought variability. Correlation and temporal correlation analyses showed that relationships between the two chronologies and self-calibrated Palmer Drought Severity Index （sc_PDSI） were significant and stable across time, demonstrating the strength of sc_PDSI in modeling drought conditions in this region. Based on the relationships, the mean sc_PDSI was reconstructed for the period from 1786 to 2013. Dry conditions prevailed during 1817-1819, 1829-1831, 1928-1931 and 1999-2001. Relatively wet periods were identified for 1792-1795 and 1954-1956. Spatial correlations with other fourteen precipitation/drought reconstructed series in previous studies revealed that in arid regions of Northwest China, long-term variability of moisture conditions was synchronous before the 1950s at a decadal scale （1791-1954）. In northwestern margin of the EASM, most of all selected reconstructions had better consistency in low-frequency variation, especially during dry periods, indicating similar regional moisture variations and analogous modes of climate forcing on tree growth in the region.

关键词： dendrochronology East Asian summer monsoon region self-calibrated Palmer Drought Severity Index Lenglongling Mountains

Tooth regeneration: a revolution in stomatology and evolution in regenerative medicine

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International journal of Oral Science 2011年第3期3卷 107-116页

作者： Sibel Yildirim Susan Y. Fu Keith Kim Hong Zhou Chang Hun Lee ang Li Sahng Gyoon Kim Shuang wang jeremy j. Mao Tissue Engineering and Regenerative Medicine Laboratory （TERML） Center for Craniofacial Regeneration Columbia University Medical Center New York NY 10032 USA Department of Basic Science Xi＇an Jiaotong University School of Stomatology Xi＇ an 710049 China

A tooth is a complex biological organ and consists of multiple tissues including the enamel, dentin, cementum and pulp. Tooth loss is the most common organ failure. Can a tooth be regenerated？ Can adult stem cells be orchestrated to regenerate tooth structures such as the enamel, dentin, cementum and dental pulp, or even an entire tooth？ If not, what are the therapeutically viable sources of stem cells for tooth regeneration？ Do stem cells necessarily need to be taken out of the body, and manipulated ex vivo before they are transplanted for tooth regeneration？ How can regenerated teeth be economically competitive with dental implants？ Would it be possible to make regenerated teeth affordable by a large segment of the population worldwide？ This review article explores existing and visionary approaches that address some of the above-mentioned questions. Tooth regeneration represents a revolution in stomatology as a shift in the paradigm from repair to regeneration： repair is by metal or artificial materials whereas regeneration is by biological restoration. Tooth regeneration is an extension of the concepts in the broad field of regenerative medicine to restore a tissue defect to its original form and function by biological substitutes.

关键词： stem cells bioactive cues biomaterials cell homing dental pulp tooth regeneration growth factors scaffold dental implants pulp regeneration

A Numerical Study Comparing the Effect on Residual Stresses of Two Different Types of Projectiles During Shot Peening

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Computers, Materials & Continua 2016年第3期51卷 203-215页

作者： j.Solórzano-López F.A.García-Pastor angélica Flores-Luna UNAM Facultad de QuímicaCiudad de MéxicoMéxico Cinvestav Unidad Saltillo CoahuilaMéxico TecNM Instituto Tecnológico de Tláhuac IIICiudad de MéxicoMéxico

Shot peening is a widely used technique to improve fatigue life in metallic *** processing technique introduces a subsurface compressive residual stress field through a plastic deformation of the surface caused by the impact of a large number of high-speed *** are a number of parameters that affect the residual stress field depth and *** effects of the impact angle,shot speed and shot geometry are currently being *** particular,substituting spherical cast shots by cylindrical cut wire shots is an attractive option,especially in terms of *** effect of shot geometry on residual stresses,however,needs to be further *** industrial-scale experimentation is costly and cumbersome,mathematical modeling offers a convenient alternative to carry out this type of *** present work shows a comparison between the residual stresses generated by the impact of spherical and cylindrical projectiles on a steel *** threedimensional model was developed using ABAQUS finite element commercial software(Release 6.12,Dassault Systémes,France).The results show that cylindrical shots generate residual stress fields t hat a re higher in magnitude than t hose generated by a spherical ***,the residual stress field of cylindrical shots impacting the surface at an oblique angle shows an important degree of *** effect is not found when spherical shots impact the surface at the same oblique angle.

关键词： Shot Peening Finite element method Residual Stresses

重组酶聚合酶扩增技术检测南美白对虾急性肝胰腺坏死病

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农业生物技术学报 2024年第4期32卷 961-973页

作者：金东升漏懿荣王瑶华段丽君李其昂陈琛闫茂仓陈炯周前进宁波大学农产品质量安全危害因子与风险防控国家重点实验室宁波大学海洋学院浙江省海洋水产养殖研究所浙江省近岸水域生物资源开发与保护重点实验室

急性肝胰腺坏死病(acute hepatopancreatic necrosis disease, AHPND)是一种新近出现的对虾(Penaeidae)细菌性疾病，给世界范围内的对虾养殖业造成了巨大的经济损失。AHPND主要由携带毒力基因pirA和pirB的弧菌(Vibrio spp.)引起。本研究... 详细信息

急性肝胰腺坏死病(acute hepatopancreatic necrosis disease, AHPND)是一种新近出现的对虾(Penaeidae)细菌性疾病，给世界范围内的对虾养殖业造成了巨大的经济损失。AHPND主要由携带毒力基因pirA和pirB的弧菌(Vibrio spp.)引起。本研究以pirA和pirB为检测靶标，分别设计和筛选特异性引物和探针，建立重组酶聚合酶扩增(recombinase polymerase amplification, RPA)方法。RPA反应在39℃下进行，反应时间设定为20 min。结果显示，针对pirA和pirB基因分别筛选到1套引物/探针组合。应用该引物/探针组合对RPA方法进行系列测试，发现引物/探针组合均能够特异性检出目标毒力基因，对溶藻弧菌(Vibrio alginolyticus)、副溶血弧菌(V. parahaemolyticus)，以及虾肝肠孢虫(Enterocytozoon hepatopenaei)等13种微生物的基因组DNA未出现扩增。灵敏度实验结果发现，使用pirA的引物/探针组合最低能够稳定检测出0.01 fg/μL的重组质粒pirAB-pMD19，而使用pirB的引物/探针组合最低能够稳定检测出0.1 fg/μL的重组质粒pirAB-pMD19。经优化，检测pirA和pirB的RPA反应的最优引物浓度为0.4μmol/L，探针浓度为0.16μmol/L。使用优化的引物/探针组合对可疑南美白对虾(Penaeus vannamei)组织样品利用RPA方法进行检测，结果显示，利用建立的RPA方法能够准确地从对虾组织样品中检测到pirA和pirB，综合检测结果与世界动物卫生组织(World Organisation for Animal Health, WOAH)推荐的PCR方法结果一致。综上，本研究分别针对pirA和pirB建立的PRA方法能够快速、准确地检出ANPND病原，而且操作简便、耗时短，有望成为AHPND病害日常监测和快速检测的重要补充。

关键词：重组酶聚合酶技术(RPA) 急性肝胰腺坏死病(AHPND) pirA pirB 检测

Phenotypic nutrient up-take differences in an alley cropping system in semi-arid Machakos, Kenya

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journal of Environmental Sciences 2001年第2期13卷 164-169页

作者： D.N. Mungai C.L.Coulson C.j. Stigter j.K. Ng’ang’a D.N.Mugendi Department of Geography University of NairobiNairdbiKenya Department of Botany University of NairobiNairobiKenya Department of Enviromnental Sciences Graduate School of Productian EcologyWageningen UniversityDuivendaal 26701 APThe Netherlands Department of Meteorology University of NairobiNairobiKenya Kenya Forestry Research Instiute(KEFRI NairobiKanya)

Alley cropping of Cassia siamea and maize was studied in semi arid Kenya for soil fertility improvement. Katumani composite maize was planted except in the short rains of 1988 (SR88) when a hybrid variety was sown. Therefore the grain yield per row increased differently in the alley cropped maize (CM). Sole maize (SM) and CM yields were higher in SR88 than in the long rains of 1988 (LR88) by 62% and 38%, while yields from the same treatments in LR89 were only 21% and 45% of those in SR88 These differences in relative maize yields are attributed to differences between the two maize varieties in competition under nutrient stress conditions.

关键词： alley cropping Cassia siamea maize nutrients maize yield semi arid condition soil moisture Kenya