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An Overview of Terahertz Antennas

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China Communications 2020年第7期17卷 124-165页

作者： Yejun He Yaling Chen Long Zhang Sai-wai wong Zhi Ning Chen Guangdong Engineering Research Center of Base Station Antennas and Propagation Shenzhen Key Laboratory of Antennas and PropagationCollege of Electronics and Information EngineeringShenzhen UniversityShenzhen 518060China Department of Electrical and Computer Engineering National University of Singapore117583Singapore

The terahertz(THz)antennas,which have features of small size,wide frequency bandwidth and high data rate,are important devices for transmitting and receiving THz electromagnetic waves in the emerging THz ***,most of THz antennas suffer from relatively high loss and low fabrication precision due to their small sizes in high frequency bands of THz ***,this paper presents a detailed overview of the most recent research on the performance improvement of THz ***,the development of THz antennas is briefly reviewed and the basic design ideas of THz antennas are ***,THz antennas are categorized as metallic antennas,dielectric antennas and new material *** that,the latest research progress in THz photoconductive antennas,THz horn antennas,THz lens antennas,THz microstrip antennas and THz on-chip antennas are *** particular,the practical difficulties for the development of THz antennas are discussed with promising *** addition,this paper also presents a short review of the process technology of THz ***,the vital challenges and the future research directions for THz antennas are presented.

关键词： sizes directions dielectric

Development of An ICR Mouse Bioassay for Toxicity Evaluation in Neurotoxic Poisoning Toxins-Contaminated Shellfish

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Biomedical and Environmental Sciences 2013年第5期26卷 346-364页

作者： wong Chun Kwan HUNG Patricia KAM kai Man Biotoxin Laboratory Microbiology DivisionPublic Health Laboratory Services BranchCentre for Health ProtectionDepartment of HealthShek Kip MeiKowloon

Objective To develop an ICR （female） mouse bioassay （MBA） for toxicity confirmation and evaluation of neurotoxins （brevetoxins）-contaminated shellfish. Methods Brevetoxins （BTX-B） as a causative agent of neurotoxic shellfish poisoning （NSP） under different shellfish matrices were intraperitoneally injected at different doses into mice to study their toxic effects and to differentiate the range of lethal and sublethal dosages. Their sensitivity and specificity were analyzed with 2 competitive ELISA kits for quantitative determination of standard BTX-B and dihydroBTX-B under different shellfish matrix-diluent combinations. Detection rates of MBA and two antibody-based assays for BTX-B from field NSP-positive shellfish samples were compared. Results BTX-B could be detected in shellfish tissues at concentration of 50-400 μg/100 g under shellfish matrix-Tween-saline media, which were appropriate to identify toxic shellfish at or above the regulatory limit （80 μg/100 g shellfish tissues）. The LD 50 identified was 455 g/kg for BTX-B under general shellfish matrices （excluding oyster matrices） dissolved in Tween-saline. The presence of shellfish matrices, of oyster matrices in particular, retarded the occurrence of death and toxicity presentation in mice. Two antibody-based assays, even in the presence of different shellfish matrix-diluent combinations, showed acceptable results in quantifying BTX-B and dihydroBTX-B well below the regulatory limit. Conclusion The two ELISA analyses agree favorably （correlation coefficient, r 0.96; Student＇s t-tests, P〉0.05） with the developed bioassay.

关键词： Antibody-based assay Brevetoxin ICR female mice LD 50 Mouse bioassay Neurotoxic shellfish poisoning

A Survey on Recent Advances and Challenges in Reinforcement Learning Methods for Task-oriented Dialogue Policy Learning

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Machine Intelligence Research 2023年第3期20卷 318-334页

作者： wai-Chung Kwan Hong-Ru Wang Hui-Min Wang Kam-Fai wong The Systems Engineering and Engineering Management Department The Chinese University of Hong KongHong Kong 999077China

Dialogue policy learning(DPL)is a key component in a task-oriented dialogue(TOD)*** goal is to decide the next action of the dialogue system,given the dialogue state at each turn based on a learned dialogue *** learning(RL)is widely used to optimize this dialogue *** the learning process,the user is regarded as the environment and the system as the *** this paper,we present an overview of the recent advances and challenges in dialogue policy from the perspective of *** specifically,we identify the problems and summarize corresponding solutions for RL-based dialogue policy *** addition,we provide a comprehensive survey of applying RL to DPL by categorizing recent methods into five basic elements in *** believe this survey can shed light on future research in DPL.

关键词： Dialogue policy learning(DPL) task-oriented dialogue system(TOD) reinforcement learning(RL) dialogue system Markov decision process

Differing coping mechanisms, stress level and anorectal physiology in patients with functional constipation

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World Journal of Gastroenterology 2005年第34期11卷 5362-5366页

作者： Annie OO Chan Cecilia Cheng wai Mo Hui Wayne HC Hu Nina YH wong KF Lam wai Man wong Kam Chuen Lai Shiu Kum Lam Benjamin CY wong Department of Medicine the University of Hong Kong Hong Kong China Division of Social Science the Hong Kong University of Science and Technology Hong Kong China Department of Medicine the University of Hong Kong Hong Kong China Department of Statistics the University of Hong Kong Hong Kong China

AIM: To investigate coping mechanisms, constipation symptoms and anorectal physiology in 80 constipated subjects and 18 ***: Constipation was diagnosed by Rome Ⅱ *** ability and anxiety/depression were assessed by validated questionnaires. Transit time and balloon distension test were ***: 34.5% patients were classified as slow transit type of constipation. The total colonic transit time (56 h vs 10 h, P＜0.0001) and rectal sensation including urge sensation (79 mL vs 63 mL, P = 0.019) and maximum tolerable volume (110 mL vs95 mL, P = 0.03) differed in patients and controls. Constipated subjects had significantly higher anxiety and depression scores and lower SF-36 scores in all categories. They also demonstrated higher scores of'monitoring' coping strategy (14+6 vs9+3, P = 0.001),which correlated with the rectal distension sensation (P = 0.005), urge sensation (P=0.002), and maximum tolerable volume (P = 0.035). The less use of blunting strategy predicted slow transit constipation in both univariate (P = 0.01) and multivariate analysis (P = 0.03).CONCLUSION: Defective or ineffective use of coping strategies may be an important etiology in functional constipation and subsequently reflected in abnormal anorectal physiology.

关键词： Constipation Anorectal physiology Coping mechanism

Improved Symmetry Property of High Order Weighted Essentially Non-Oscillatory Finite Difference Schemes for Hyperbolic Conservation Laws

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Advances in Applied Mathematics and Mechanics 2018年第6期10卷 1418-1439页

作者： wai Sun Don Peng Li Kwun Ying wong Zhen Gao School of Mathematical Sciences Ocean University of ChinaQingdao 266100ShandongChina Department of Mathematics and Physics Shijiazhuang Tiedao UniversityShijiazhuang 050043HebeiChina N.T.Heung Yee Kuk Yuen Long District Secondary School Hong Kong

This study aims to investigate the rapid loss of numerical symmetry for problems with symmetrical initial conditions and boundary conditions when solved by the seventh and higher order nonlinear characteristic-wise weighted essentially non-oscillatory(WENO)finite difference *** the one-dimensional double rarefaction wave problem and the Sedov blast-wave problems,and the twodimensional Rayleigh-Taylor instability(RTI)problem as examples,we illustrate numerically that the sensitive interaction of the round-off error due to the numerical unstable explicit form of the local lower order smoothness indicators in the nonlinear weights definition,which are often given and used in the literature,and the nonlinearity of the WENO scheme are responsible for the rapid growth of asymmetry of an otherwise symmetric *** equivalent but compact and numerical stable compact form of the local lower order smoothness indicators is suggested for delaying the onset of and reducing the magnitude of the symmetry *** benefits of using the compact form of the local lower order smoothness indicators should also be applicable to non-symmetrical strongly non-linear problems in terms of improved numerical stability,reduced rounding errors and increased computational efficiency.

关键词： Weighted essentially non-oscillatory symmetry smoothness indicator hyperbolic conservation laws

A novel reductive ring-opening reaction of isoxazolidine to form functionalized 1,3-aminoalcohol

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Chinese Chemical Letters 2007年第6期18卷 629-632页

作者： Wing Hong Chan Albert W.M. Lee wai Yeung wong Department of Chemistry Hong Kong Baptist University Kowloog Tong Hong Kong

Reductive cleavage of the NO bond of isoxazolidine ring with catalytic hydrogenation over Raney nickel was described. Bicyclic isoxazolidines could be effectively converted into the corresponding 1,3-amino-alcohol possessing a sultone or sultam moiety with high conversion and yield when the hydrogenation was catalyzed by freshly prepared Raney nickel under a pressure of 40 psi in the presence of triethylamine.

关键词： Isoxazolidine Hydrogenation Raney nickel 1,3-Amino-alcohol

Cancers of the lung, head and neck on the rise: perspectives on the genotoxicity of air pollution

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Chinese Journal of Cancer 2014年第10期33卷 476-480页

作者： Ian Chi Kei wong Yuen-Keng Ng Vivian wai Yan Lui Pharmacogenomics and Precision Therapeutics Laboratory Department of Pharmacology and PharmacyLi Ka Shing Faculty of MedicineThe University of Hong Kong

Outdoor air pollution has been recently classified as a class I human carcinogen by the World Health Organization(WHO). Cumulative evidence from across the globe shows that polluted air is associated with increased risk of lung, head and neck, and nasopharyngeal cancers—all of which affect the upper aerodigestive tract. Importantly, these cancers have been previously linked to smoking. In this article, we review epidemiologic and experimental evidence of the genotoxic and mutagenic effects of air pollution on DNA, purportedly a key mechanism for cancer development. The alarming increase in cancers of the upper aerodigestive tract in Asia suggests a need to focus government efforts and research on reducing air pollution, promoting clean energy, and investigating the carcinogenic effects of air pollution on humans.

关键词：空气污染头颈部癌症遗传毒性肺癌世界卫生组织上升实验证据

Metallated conjugation in small-sized-molecular donors for solution-processed organic solar cells

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Science China Chemistry 2015年第2期58卷 347-356页

作者： Chaohua Cui Yunye Zhang Wallace C.H.Choy Hua Li wai-Yeung wong Institute of Molecular Functional Materials Department of Chemistry and Institute of Advanced Materials Hong Kong Baptist University Department of Electrical and Electronic Engineering The University of Hong Kong College of Life and Environmental Sciences & Beijing Engineering Research Center of Food Environment and Public Health Minzu University of China HKBU Institute of Research and Continuing Education Shenzhen Virtual University Park

Four metallated conjugated oligothiophenes, S-1, S-2, S-3 and S-4, with platinum（II） aryleneethynylenes as the electron-rich building block were synthesized to investigate their physicochemical and photovoltaic properties. These small molecules possess fairly low-lying HOMO energy levels which match with the LUMO energy level of the electron acceptor PC70BM （[6,6]-phenyl-C71-butyric acid methyl ester）. Using the simple process of spin-coating solution fabrication technique, S-I：PC70BM （1：4, w/w） based organic solar cells exhibiting a high Voc of 0.913 V, with a PCE value of 0.88% were developed. In contrast, the OSC device based on S-2：PC70BM （3：7, w/w） displayed a higher PCE of 1.59% with a higher Jsc value of 5.89 mA cm^-2. The device based on S-4：PCToBM （1：4, w/w） exhibited a PCE value of 1.56%, with a Voc of 0.917 V.

关键词： platinum acetylide photovoltaics organic solar cell oligothiophene

Rapid testing methods for food contaminants and toxicants

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Journal of Integrative Agriculture 2015年第11期14卷 2243-2264页

作者： Jiachi Chiou Arthur Ho Hon Leung Hang wai Lee Wing-tak wong Department of Applied Biology and Chemical Technology Food Safety and Technology Research CenterThe Hong Kong Polytechnic University Shenzhen Key Laboratory for Food Biological Safety Control Food Safety and Technology Research CentreThe Hong Kong Polytechnic University Shenzhen Research Institute

Food safety is one of the major concerns in every country regardless of the economic and social development. The frequent occurrence of food scandals in the world has led the Chinese government to implement several strategies to fortify the food supply system to a high food safety standard. This relies heavily on laboratory testing services but conventional methods for detection of food contaminants and toxicants are limited by sophisticated sample preparation procedures, long analysis time, large instruments and professional personnel to meet the increasing demands. In this review, we have incorporated most of the current and potential rapid detection methods for many notorious food contaminants and toxicants including microbial agents, toxic ions, pesticides, veterinary drugs and preservatives, as well as detection of genetically modified food genes and adulterated edible oil. Development of rapid, accurate, easy-to-use and affordable testing methods could urge food handlers and the public to actively screen for food contaminants and toxicants instead of passively relying on monitoring by the government examination facility. This review also provides several recommendations including how to encourage the public to engage in the food safety management system and provide optimal education and financial assistance that may improve the current Chinese food safety control system.

关键词： rapid testing food contaminants and toxins microbial agents pesticides veterinary drugs preservatives formaldehyde nitrite nitrate test strips