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Your search keyword '"Ho, W. K."' showing total 305 results
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305 results on '"Ho, W. K."'

1. Strain in Epitaxial High-Index Bi2Se3(221) Films Grown by Molecular-Beam Epitaxy

Author

Li, B., Chen, W. G., Guo, X., Ho, W. K., Dai, X. Q., Jia, J. F., and Xie, M. H.

Subjects
Condensed Matter - Materials Science
Abstract

High-index Bi2Se3(221) film has been grown on In2Se3-buffered GaAs(001), in which a much retarded strain relaxation dynamics is recorded. The slow strain-relaxation process of in epitaxial Bi2Se3(221) can be attributed to the layered structure of Bi2Se3 crystal, where the epifilm grown along [221] is like a pile of weakly-coupled quintuple layer slabs stacked side-by-side on substrate. Finally, we have revealed the strong chemical bonding at the interface of Bi2Se3 and In2Se3 by plotting differential charge contour calculated by first-principle method. This study points to the feasibility of achieving strained TIs for manipulating the properties of topological systems.

Published
2016
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2. Molecular-beam epitaxy of monolayer and bilayer WSe2: A scanning tunneling microscopy/spectroscopy study and deduction of exciton binding energy

Author

Liu, H. J., Jiao, L., Xie, L., Yang, F., Chen, J. L., Ho, W. K., Gao, C. L., Jia, J. F., Cui, X. D., and Xie, M. H.

Subjects
Condensed Matter - Materials Science
Abstract

Interests in two-dimensional transition-metal dichalcogenides have prompted some recent efforts to grow ultrathin layers of these materials epitaxially using molecular-beam epitaxy. However, growths of monolayer and bilayer WSe2, an important member of the transition-metal dichalcogenides family, by the molecular-beam epitaxy method remain uncharted probably because of the difficulty in generating tungsten fluxes from the elemental source. In this work, we present a scanning tunneling microscopy and spectroscopy study of molecular-beam epitaxy-grown WSe2 monolayer and bilayer, showing atomically flat epifilm with no domain boundary defect. This contrasts epitaxial MoSe2 films grown by the same method, where a dense network of the domain boudaries defects is present. The scanning tunneling spectroscopy measurements of monolayer and bilayer WSe2 domains of the same sample reveal not only the bandgap narrowing upon increasing the film thickness from monolayer to bilayer, but also a band-bending effect across the boundary between monolayer and bilayer domains. This band-bending appears to be dictated by the edge states at steps of the bilayer islands. Finally, comparison is made between the scanning tunneling spectroscopy-measured electronic bandgaps with the exciton emission energies measured by photoluminescence, and the exciton binding energies in monolayer and bilayer WSe2/MoSe2 are thus estimated.

Published
2015
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3. Vehicular emission of volatile organic compounds (VOCs) from a tunnel study in Hong Kong

Author

Ho, K. F, Lee, S. C, Ho, W. K, Blake, D. R, Cheng, Y., Li, Y. S, Ho, S. S. H, Fung, K., Louie, P. K. K, and Park, D.

Subjects
tuscarora mountain tunnels, aromatic-hydrocarbons pahs, vehicle emissions, source apportionment, carbonyl-compounds, urban atmosphere, fort mchenry, exhaust, engine, road
Abstract

Vehicle emissions of volatile organic compounds (VOCs) were determined at the Shing Mun Tunnel, Hong Kong in summer and winter of 2003. One hundred and ten VOCs were quantified in this study. The average concentration of the total measured VOCs at the inlet and outlet of the tunnel were 81 250 pptv and 117 850 pptv, respectively. Among the 110 compounds, ethene, ethyne and toluene were the most abundant species in the tunnel. The total measured VOC emission factors ranged from 67 mg veh(-1) km(-1) to 148 mg veh(-1) km(-1), with an average of 115 mg veh(-1) km(-1). The five most abundant VOCs observed in the tunnel were, in decreasing order, ethene, toluene, n-butane, propane and i-pentane. These five most abundant species contributed over 38% of the total measured VOCs emitted. The high propane and n-butane emissions were found to be associated with liquefied petroleum gas (LPG)-fueled taxis. Fair correlations were observed between marker species (ethene, i-pentane, n-nonane, and benzene, toluene, ethylbenzene and xylenes - BTEX) with fractions of gasoline-fueled or diesel-fueled vehicles. Moreover, ethene, ethyne, and propene are the key species that were abundant in the tunnel but not in gasoline vapors or LPG. The ozone formation potential from the VOCs in Hong Kong was evaluated by the maximum increment reactivity (MIR). It was found to be 568 mg of ozone per vehicle per kilometer traveled. Among them, ethene, propene and toluene contribute most to the ozone-formation reactivity.

Published
2009

5. Genome-wide meta-analysis identifies six novel loci associated with habitual coffee consumption

Author

Cornelis, M C, Byrne, E M, Esko, T, Nalls, M A, Ganna, A, Paynter, N, Monda, K L, Amin, N, Fischer, K, Renstrom, F, Ngwa, J S, Huikari, V, Cavadino, A, Nolte, I M, Teumer, A, Yu, K, Marques-Vidal, P, Rawal, R, Manichaikul, A, Wojczynski, M K, Vink, J M, Zhao, J H, Burlutsky, G, Lahti, J, Mikkilä, V, Lemaitre, R N, Eriksson, J, Musani, S K, Tanaka, T, Geller, F, Luan, J, Hui, J, Mägi, R, Dimitriou, M, Garcia, M E, Ho, W-K, Wright, M J, Rose, L M, Magnusson, P K E, Pedersen, N L, Couper, D, Oostra, B A, Hofman, A, Ikram, M A, Tiemeier, H W, Uitterlinden, A G, van Rooij, F J A, Barroso, I, Johansson, I, Xue, L, Kaakinen, M, Milani, L, Power, C, Snieder, H, Stolk, R P, Baumeister, S E, Biffar, R, Gu, F, Bastardot, F, Kutalik, Z, Jacobs, Jr, D R, Forouhi, N G, Mihailov, E, Lind, L, Lindgren, C, Michaëlsson, K, Morris, A, Jensen, M, Khaw, K-T, Luben, R N, Wang, J J, Männistö, S, Perälä, M-M, Kähönen, M, Lehtimäki, T, Viikari, J, Mozaffarian, D, Mukamal, K, Psaty, B M, Döring, A, Heath, A C, Montgomery, G W, Dahmen, N, Carithers, T, Tucker, K L, Ferrucci, L, Boyd, H A, Melbye, M, Treur, J L, Mellström, D, Hottenga, J J, Prokopenko, I, Tönjes, A, Deloukas, P, Kanoni, S, Lorentzon, M, Houston, D K, Liu, Y, Danesh, J, Rasheed, A, Mason, M A, Zonderman, A B, Franke, L, Kristal, B S, Karjalainen, J, Reed, D R, Westra, H-J, Evans, M K, Saleheen, D, Harris, T B, Dedoussis, G, Curhan, G, Stumvoll, M, Beilby, J, Pasquale, L R, Feenstra, B, Bandinelli, S, Ordovas, J M, Chan, A T, Peters, U, Ohlsson, C, Gieger, C, Martin, N G, Waldenberger, M, Siscovick, D S, Raitakari, O, Eriksson, J G, Mitchell, P, Hunter, D J, Kraft, P, Rimm, E B, Boomsma, D I, Borecki, I B, Loos, R J F, Wareham, N J, Vollenweider, P, Caporaso, N, Grabe, H J, Neuhouser, M L, Wolffenbuttel, B H R, Hu, F B, Hyppönen, E, Järvelin, M-R, Cupples, L A, Franks, P W, Ridker, P M, van Duijn, C M, Heiss, G, Metspalu, A, North, K E, Ingelsson, E, Nettleton, J A, van Dam, R M, and Chasman, D I

Published
2015
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20. Fifteen new risk loci for coronary artery disease highlight arterial-wall-specific mechanisms

Author

Howson, JMM, Zhao, W, Barnes, DR, Ho, W-K, Young, R, Paul, DS, Waite, LL, Freitag, DF, Fauman, EB, Salfati, EL, Sun, BB, Eicher, JD, Johnson, AD, Sheu, WHH, Nielsen, SF, Lin, W-Y, Surendran, P, Malarstig, A, Wilk, JB, Tybjærg-Hansen, A, Rasmussen, KL, Kamstrup, PR, Deloukas, P, Erdmann, J, Kathiresan, S, Samani, NJ, Schunkert, H, Watkins, H, CARDIoGRAMplusC4D, Do, R, Rader, DJ, Johnson, JA, Hazen, SL, Quyyumi, AA, Spertus, JA, Pepine, CJ, Franceschini, N, Justice, A, Reiner, AP, Buyske, S, Hindorff, LA, Carty, CL, North, KE, Kooperberg, C, Boerwinkle, E, Young, K, Graff, M, Peters, U, Absher, D, Hsiung, CA, Lee, W-J, Taylor, KD, Chen, Y-H, Lee, I-T, Guo, X, Chung, R-H, Hung, Y-J, Rotter, JI, Juang, J-MJ, Quertermous, T, Wang, T-D, Rasheed, A, Frossard, P, Alam, DS, Majumder, AAS, Di Angelantonio, E, Chowdhury, R, EPIC-CVD, Chen, Y-DI, Nordestgaard, BG, Assimes, TL, Danesh, J, Butterworth, AS, Saleheen, D, Howson, Joanna [0000-0001-7618-0050], Barnes, Daniel [0000-0002-3781-7570], Paul, Dirk [0000-0002-8230-0116], Sun, Ben [0000-0001-6347-2281], Surendran, Praveen [0000-0002-4911-6077], Di Angelantonio, Emanuele [0000-0001-8776-6719], Chowdhury, Rajiv [0000-0003-4881-5690], Danesh, John [0000-0003-1158-6791], Butterworth, Adam [0000-0002-6915-9015], and Apollo - University of Cambridge Repository

Subjects
Male, Genotype, Quantitative Trait Loci, Coronary Artery Disease, Cardiovascular, Medical and Health Sciences, Risk Factors, Vascular, Cell Adhesion, Genetics, Humans, 2.1 Biological and endogenous factors, Genetic Predisposition to Disease, Polymorphism, Aetiology, EPIC-CVD, Heart Disease - Coronary Heart Disease, screening and diagnosis, Chemotaxis, Human Genome, Arteries, Single Nucleotide, Leukocyte, Biological Sciences, Atherosclerosis, cardiovascular diseases, Histone Code, Detection, Heart Disease, genome-wide association studies, Muscle, Female, Smooth, Energy Metabolism, CARDIoGRAMplusC4D, Genome-Wide Association Study, Biotechnology, 4.2 Evaluation of markers and technologies, Developmental Biology
Abstract

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Although 58 genomic regions have been associated with CAD thus far, most of the heritability is unexplained, indicating that additional susceptibility loci await identification. An efficient discovery strategy may be larger-scale evaluation of promising associations suggested by genome-wide association studies (GWAS). Hence, we genotyped 56,309 participants using a targeted gene array derived from earlier GWAS results and performed meta-analysis of results with 194,427 participants previously genotyped, totaling 88,192 CAD cases and 162,544 controls. We identified 25 new SNP-CAD associations (P < 5 × 10(-8), in fixed-effects meta-analysis) from 15 genomic regions, including SNPs in or near genes involved in cellular adhesion, leukocyte migration and atherosclerosis (PECAM1, rs1867624), coagulation and inflammation (PROCR, rs867186 (p.Ser219Gly)) and vascular smooth muscle cell differentiation (LMOD1, rs2820315). Correlation of these regions with cell-type-specific gene expression and plasma protein levels sheds light on potential disease mechanisms.

Published
2017

23. A Study on Rank Commutators of Special Families of Matrices.

Author

Dong, F., Ho, W. K., and Zhao, D.

Subjects
*MATRICES (Mathematics), *COMMUTATORS (Operator theory), *LINEAR operators, *ALGEBRA, *MATHEMATICS
Abstract

Given two square matrices A, B of the same size, the two matrices AB and BA may have different ranks. A non-zero square matrix A is called a rankcommutator of a family L of n × n matrices if rank(AL) = rank(LA) holds for every L in L. Let L* denote the family of all rank-commutators of L. In this paper, we investigate the members of L* for the following families L of n×n matrices: all non-zero symmetric matrices; all diagonal matrices; all diagonalizable matrices. In the process, some new notions in linear algebra are created, such as "rank-symmetric matrices" and "determinant equivalent matrices", which might be useful for other study on ranks. A few problems for further study are posed at the end of the paper. [ABSTRACT FROM AUTHOR]

Published
2018

35. Ethyl acetate fraction of the root ofrubia cordifoliaL. inhibits keratinocyte proliferationin vitroand promotes keratinocyte differentiationin vivo: potential application for psoriasis treatment

Author

Lin, Z. X., primary, Jiao, B. W., additional, Che, C. T., additional, Zuo, Z., additional, Mok, C. F., additional, Zhao, M., additional, Ho, W. K. K., additional, Tse, W. P., additional, Lam, K. Y., additional, Fan, R. Q., additional, Yang, Z. J., additional, and Cheng, C. H. K., additional

Published
2009
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