Effect of sintering holding time on the properties and low-temperature degradation behaviour of manganese oxide-doped Y-TZP ceramic

S.M. Kwa,S. Ramesh,L.T. Bang,Y.H. Wong,W.J. Kelvin Chew,C.Y. Tan,J. Purbolaksono,H. Misran,W.D. Teng 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.2

The sintering of yttria-tetragonal zirconia polycrystals (Y-TZP) is commonly carried at a predefined temperature using a long holding time of 2 hours. This often has resulted in grain coarsening which affects the mechanical properties of the sintered body and low temperature degradation (LTD) behaviour of the ceramic when exposed to moist environment. In this research, the effect of using a short holding time of 1 min. during sintering coupled with small amounts (0.5 and 1 wt%) of manganese oxide, MnO2 as dopant on the mechanical properties and LTD behaviour of 3 mol% Y-TZP were investigated. The results showed that the mechanical properties improved significantly with the addition of 0.5 wt% MnO2 for the 1-min. and 12-min. holding time samples when compared to 2 hours holding time sintered at the same temperature of 1350 ℃. Nevertheless, regardless of the holding time employed, the 1 wt% MnO2 addition was not effective in improving the mechanical properties and ageing resistance of Y-TZP ceramic.

Free vibration characteristics of horizontally curved composite plate girder bridges M.Y.

M.Y. Wong,S.A. Osman,N.E. Shanmugam 국제구조공학회 2010 Steel and Composite Structures, An International J Vol.10 No.4

This paper is concerned with free vibration characteristics and natural frequency of horizontally curved composite plate girder bridges. Three-dimensional finite element models are developed for the girders using the software package LUSAS and analyses carried out on the models. The validity of the finite element models is first established through comparison with the corresponding results published by other researchers. Studies are then carried out to investigate the effects of total number of girders, number of cross-frames and curvature on the free vibration response of horizontally curved composite plate girder bridges. The results confirm the fact that bending modes are always coupled with torsional modes for horizontally curved bridge girder systems. The results show that the first bending mode is influenced by composite action between the concrete deck and steel beam at low subtended angle but, on the girders with larger subtended angle at the centre of curvature such influence is non-existence. The increase in the number of girders results in higher natural frequency but at a decreasing rate. The in-plane modes viz. longitudinal and arching modes are significantly influenced by composite action and number of girders. If no composite action is taken into account the number of girders has no significant effect for the in-plane modes.

MOLECULAR AND ATOMIC GAS IN THE LARGE MAGELLANIC CLOUD. II. THREE-DIMENSIONAL CORRELATION BETWEEN CO AND H I

Fukui, Y.,Kawamura, A.,Wong, T.,Murai, M.,Iritani, H.,Mizuno, N.,Mizuno, Y.,Onishi, T.,Hughes, A.,Ott, J.,Muller, E.,Staveley-Smith, L.,Kim, S. IOP Publishing 2009 The Astrophysical journal Vol.705 No.1

<P>We compare the CO (J = 1-0) and HI emission in the Large Magellanic Cloud in three dimensions, i.e., including a velocity axis in addition to the two spatial axes, with the aim of elucidating the physical connection between giant molecular clouds (GMCs) and their surrounding Hi gas. The CO J = 1-0 data set is from the second NANTEN CO survey and the HI data set is from the merged Australia Telescope Compact Array ( ATCA) and Parkes Telescope surveys. The major findings of our analysis are as follows: (1) GMCs are associated with an envelope of HI emission, (2) in GMCs [average CO intensity] proportional to [ average Hi intensity](1.1 +/- 0.1), and (3) the HI intensity tends to increase with the star formation activity within GMCs, from Type I to Type III. An analysis of the HI envelopes associated with GMCs shows that their average line width is 14 km s(-1) and the mean density in the envelope is 10 cm(-3). We argue that the HI envelopes are gravitationally bound by GMCs. These findings are consistent with a continual increase in the mass of GMCs via HI accretion at an accretion rate of 0.05 M-circle dot yr(-1) over a timescale of 10 Myr. The growth of GMCs is terminated via dissipative ionization and/or stellar-wind disruption in the final stage of GMC evolution.</P>

Physical properties of giant molecular clouds in the Large Magellanic Cloud

Hughes, A.,Wong, T.,Ott, J.,Muller, E.,Pineda, J. L.,Mizuno, Y.,Bernard, J.-P.,Paradis, D.,Maddison, S.,Reach, W. T.,Staveley-Smith, L.,Kawamura, A.,Meixner, M.,Kim, S.,Onishi, T.,Mizuno, N.,Fukui, Y. Blackwell Publishing Ltd 2010 Monthly notices of the Royal Astronomical Society Vol.406 No.3

<P>ABSTRACT</P><P>The Magellanic Mopra Assessment (MAGMA) is a high angular resolution <SUP>12</SUP>CO (<I>J</I>= 1 → 0) mapping survey of giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud using the Mopra Telescope. Here we report on the basic physical properties of 125 GMCs in the LMC that have been surveyed to date. The observed clouds exhibit scaling relations that are similar to those determined for Galactic GMCs, although LMC clouds have narrower linewidths and lower CO luminosities than Galactic clouds of a similar size. The average mass surface density of the LMC clouds is 50 M<SUB>⊙</SUB> pc<SUP>−2</SUP>, approximately half that of GMCs in the inner Milky Way. We compare the properties of GMCs with and without signs of massive star formation, finding that non-star-forming GMCs have lower peak CO brightness than star-forming GMCs. We compare the properties of GMCs with estimates for local interstellar conditions: specifically, we investigate the H <SMALL>I</SMALL> column density, radiation field, stellar mass surface density and the external pressure. Very few cloud properties demonstrate a clear dependence on the environment; the exceptions are significant positive correlations between (i) the H <SMALL>I</SMALL> column density and the GMC velocity dispersion, (ii) the stellar mass surface density and the average peak CO brightness and (iii) the stellar mass surface density and the CO surface brightness. The molecular mass surface density of GMCs without signs of massive star formation shows no dependence on the local radiation field, which is inconsistent with the photoionization-regulated star formation theory proposed by McKee. We find some evidence that the mass surface density of the MAGMA clouds increases with the interstellar pressure, as proposed by Elmegreen, but the detailed predictions of this model are not fulfilled once estimates for the local radiation field, metallicity and GMC envelope mass are taken into account.</P>

Indium oxide, tin oxide and indium tin oxide nanostructure growth by vapor deposition

M.K. Fung,K.K. Wong,X.Y. Chen,Y.F. Chan,A.M.C. Ng,A.B. Djurišić,W.K. Chan 한국물리학회 2012 Current Applied Physics Vol.12 No.3

Indium oxide, tin oxide and indium tin oxide nanowires have been grown by vapor deposition on Si and quartz substrates. Under the growth conditions used, pure SiOx nanowires, a mixture of SiOx and indium oxide, tin oxide or indium tin oxide nanostructures, or pure indium oxide, tin oxide or indium tin oxide nanostructures could be obtained at different substrate temperatures. The growth mechanism of the obtained nanostructures at different substrate temperatures is discussed. Optical and electrical properties of the deposited pure indium oxide, tin oxide or indium tin oxide nanostructures have been measured, and low sheet resistances on quartz substrates have been obtained for indium oxide and indium tin oxide nanostructures.

Brain metastases in Asian HER2-positive breast cancer patients: anti-HER2 treatments and their impact on survival

Yap, Y S,Cornelio, G H,Devi, B C R,Khorprasert, C,Kim, S B,Kim, T Y,Lee, S C,Park, Y H,Sohn, J H,Sutandyo, N,Wong, D W Y,Kobayashi, M,Landis, S H,Yeoh, E M,Moon, H,Ro, J Nature Publishing Group 2012 The British journal of cancer Vol.107 No.7

<P><B>Background:</B></P><P>In Asia, large-scale studies on anti-HER2 treatment in HER2-positive breast cancer patients with brain metastases are limited. We studied the treatment patterns of these patients in Asia to evaluate the impact of anti-HER2 treatment on the time to occurrence of brain metastases (TTBM) and survival after brain metastasis (BM).</P><P><B>Methods:</B></P><P>A retrospective study of HER2-positive breast cancer patients diagnosed with BM between January 2006 and December 2008 in six Asian countries was conducted. Demographics, tumour characteristics, treatment details, and events dates were collected from medical records.</P><P><B>Results:</B></P><P>Data from 280 patients were analysed. Before BM, 63% received anti-HER2 treatment. These patients had significantly longer TTBM than those without anti-HER2 treatment (median 33 <I>vs</I> 19 months; <I>P</I><0.002). After BM, 93% received radiotherapy, 57% received chemotherapy, and 41% received anti-HER2 treatment (trastuzumab and/or lapatinib). Use of both anti-HER2 agents, primarily sequentially, after BM demonstrated the longest survival after BM and was associated with a significant survival benefit over no anti-HER2 treatment (median 26 <I>vs</I> 6 months; hazard ratio 0.37; 95% CI 0.19–0.72).</P><P><B>Conclusion:</B></P><P>Anti-HER2 treatment before BM was associated with longer TTBM. Anti-HER2 treatment after BM was associated with a survival benefit, especially when both trastuzumab and lapatinib were utilised.</P>

제4차 산업혁명시대 캐나다 노인의 스마트 에이징과 건강에의 영향

Roger Y.M. Wong 한국노년학회 2017 한국노년학회 학술발표논문집 Vol.2017 No.국제학술

제4차 산업혁명시대 캐나다 노인의 스마트 에이징과 건강에의 영향

Roger Y.M. Wong 한국노년학회 2017 한국노년학회 학술발표논문집 Vol.2017 No.6

Edge perturbation on electronic properties of boron nitride nanoribbons

K.L. Wong,K.W. Lai,M.W. Chuan,Y. Wong,A. Hamzah,S. Rusli,N.E. Alias,S. Mohamed Sultan,C.S. Lim,M.L.P. Tan Techno-Press 2023 Advances in nano research Vol.15 No.5

Hexagonal boron nitride (h-BN), commonly referred to as Boron Nitride Nanoribbons (BNNRs), is an electrical insulator characterized by high thermal stability and a wide bandgap semiconductor property. This study delves into the electronic properties of two BNNR configurations: Armchair BNNRs (ABNNRs) and Zigzag BNNRs (ZBNNRs). Utilizing the nearest-neighbour tight-binding approach and numerical methods, the electronic properties of BNNRs were simulated. A simplifying assumption, the Hamiltonian matrix is used to compute the electronic properties by considering the self-interaction energy of a unit cell and the interaction energy between the unit cells. The edge perturbation is applied to the selected atoms of ABNNRs and ZBNNRs to simulate the electronic properties changes. This simulation work is done by generating a custom script using numerical computational methods in MATLAB software. When benchmarked against a reference study, our results aligned closely in terms of band structure and bandgap energy for ABNNRs. However, variations were observed in the peak values of the continuous curves for the local density of states. This discrepancy can be attributed to the use of numerical methods in our study, in contrast to the semi-analytical approach adopted in the reference work.

What attracts young people to become teachers? A comparative study of pre-service student teachers’ motivation to become teachers in Hong Kong and Macau

Tang Sylvia Y. F.,Wong P. M.,Wong Angel K. Y.,Cheng May M. H. 서울대학교 교육연구소 2018 Asia Pacific Education Review Vol.19 No.3

This article reports a comparative study on the reasons for pre-service student teachers becoming teachers in Hong Kong and Macau. The study adopted a mixed methods research design, with 459 and 137 student teachers completing a questionnaire on teaching motivation and 35 and 15 student teachers joining a follow-up interview in Hong Kong and Macau, respectively. The study found that student teachers in both societies share commonality in their altruistic and intrinsic motivations, i.e. a sense of vocation. The difference in student teachers’ motivation reflects the contrasting perceptions of teachers’ work and the teaching profession in connection with the different educational systemic factors in Macau and Hong Kong. Government-initiated quantitative expansion and quality enhancement in education set the backdrop of an aspiring teaching profession with promising prospects as perceived by the student teachers in Macau. In contrast, the move towards "centralized-decentralization" with a focus on excellence, competition and accountability in education at a time of teacher surplus results in a demanding profession with gloomy prospects as perceived by the Hong Kong student teachers. These differences add to our understanding of how the development trajectories of different education systems and teaching professions influence young people’s motivation to become teachers in different societies. The study also provides insights for initial teacher education and offers suggestions for the education communities of the two societies.