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.

本態性 血小板 過多症에서의 치료적 혈소판 반출치험 1예

김진주,이경원,송경순,이삼열,신용운,한지숙,고윤웅 大韓血液學會 1985 大韓血液學會誌 Vol.20 No.1

Enhancement of Excretory Production of an Exoglucanase from Escherichia coli with Phage Shock Protein A (PspA) Overexpression

( Y. Y. Wang ),( Z. B. Fu ),( K. L. Ng ),( C. C. Lam ),( A. K. N. Chan ),( K. F. Sze ),( W. K. R. Wong ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.6

Production of recombinant proteins by excretory expression has many advantages over intracellular expression in Escherichia coli. Hyperexpression of a secretory exoglucanase, Exg, of Cellulomonas fimi was previously shown to saturate the SecYEG pathway and result in dramatic cell death of E. coli. In this study, we demonstrated that overexpression of the PspA in the JM101(pM1VegGcexL-pspA) strain enhanced excretion of Exg to 1.65 U/ml using shake-flask cultivation, which was 80% higher than the highest yield previously obtained from the optimized JM101(pM1VegGcexL) strain. A much higher excreted Exg activity of 4.5 U/ml was further achieved with high cell density cultivation using rich media. Furthermore, we showed that the PspA overexpression strain enjoyed an elevated critical value (CV), which was defined as the largest quotient between the intracellular unprocessed precursor and its secreted mature counterpart that was still tolerable by the host cells prior to the onset of cell death, improving from the previously determined CV of 20/80 to the currently achieved CV of 45/55 for Exg. The results suggested that the PspA overexpression strain might tolerate a higher level of precursor Exg making use of the SecYEG pathway for secretion. The reduced lethal effect might be attributable to the overexpressed PspA, which was postulated to be able to reduce membrane depolarization and damage. Our findings introduce a novel strategy of the combined application of metabolic engineering and construct optimization to the attainment of the best possible E. coli producers for secretory/excretory production of recombinant proteins, using Exg as the model protein.

Is Adjuvant Transarterial Chemoembolization Useful for Hepatocellular Carcinoma?

( Wong Hoi She ),( Cheung Tan To ),( Simon H. Y. Tsang ),( Wing Chiu Dai ),( Albert C. Y. Chan ),( Kenneth S. H. Chok ),( Kelvin K. C. Ng ),( Chung Mau Lo ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: Hepatectomy is the well-established curative treatment for hepatocellular carcinoma (HCC). However, adjuvant therapy is still controversial. This study tried to look into the effect of transarterial chemoembolization (TACE) in patients receiving hepatectomy for HCC. Methods: This is a retrospective study held in a single institution using prospectively maintained database for all the patients who underwent hepatectomy for HCC between January 2000 - December 2015. The perioperative details, pathological data and outcome were studied. Patients were matched at 1:10 ratio with comparable tumor size, number, indocyanine green retention test at 15 minutes, Child’s grading and tumor staging. The Kaplan-Meier method was used for survival analysis. The log-rank test was used for survival comparison. Results: There were total 1316 patients underwent hepatectomy for HCC. 38 patients with TACE were identified, and matched with 380 patients without TACE. The patients’ characteristics including age, sex, comorbidity, Child’s grading, ICG, tumor size and numbers were the same. The median sizes of the tumor were similar (9cm in TACE vs 8cm). There was no difference in terms of intraoperative management, extent of hepatectomy and postoperative complications. There were more patients with margin involvement in TACE group (23.7% vs 7.9%, p=0.004). The staging of the disease showed no significant difference in both groups. The disease free survival was similar (12.6 (TACE) vs 10.1months, p=0.794). There was no difference in overall survival with median survival of 27.8 (TACE) vs 36.9 months (5-year overall survival of 27.9% vs 41.2%, p=0.941). Conclusions: Margin involvement was known to be adverse factor for survival. Adjuvant TACE may benefit high-risk HCC patients with margin involvement as shown to have similar survival for those patients without margin involvement.

Structural health rating (SHR)-oriented 3D multi-scale finite element modeling and analysis of Stonecutters Bridge

Y.Q. Ni,X.F. Li,K.Y. Wong,K.W.Y. Chan 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.1

The Stonecutters Bridge (SCB) in Hong Kong is the third-longest cable-stayed bridge in the world with a main span stretching 1,018 m between two 298 m high single-leg tapering composite towers. A Wind and Structural Health Monitoring System (WASHMS) is being implemented on SCB by the Highways Department of The Hong Kong SAR Government, and the SCB-WASHMS is composed of more than 1,300 sensors in 15 types. In order to establish a linkage between structural health monitoring and maintenance management, a Structural Health Rating System (SHRS) with relevant rating tools and indices is devised. On the basis of a 3D space frame finite element model (FEM) of SCB and model updating, this paper presents the development of an SHR-oriented 3D multi-scale FEM for the purpose of load-resistance analysis and damage evaluation in structural element level, including modeling, refinement and validation of the multi-scale FEM. The refined 3D structural segments at deck and towers are established in critical segment positions corresponding to maximum cable forces. The components in the critical segment region are modeled as a full 3D FEM and fitted into the 3D space frame FEM. The boundary conditions between beam and shell elements are performed conforming to equivalent stiffness, effective mass and compatibility of deformation. The 3D multi-scale FEM is verified by the in-situ measured dynamic characteristics and static response. A good agreement between the FEM and measurement results indicates that the 3D multi-scale FEM is precise and efficient for WASHMS and SHRS of SCB. In addition, stress distribution and concentration of the critical segments in the 3D multi-scale FEM under temperature loads, static wind loads and equivalent seismic loads are investigated. Stress concentration elements under equivalent seismic loads exist in the anchor zone in steel/concrete beam and the anchor plate edge in steel anchor box of the towers.

MOLECULAR AND ATOMIC GAS IN THE LARGE MAGELLANIC CLOUD. I. CONDITIONS FOR CO DETECTION

Wong, T.,Hughes, A.,Fukui, Y.,Kawamura, A.,Mizuno, N.,Ott, J.,Muller, E.,Pineda, J. L.,Welty, D. E.,Kim, S.,Mizuno, Y.,Murai, M.,Onishi, T. IOP Publishing 2009 The Astrophysical journal Vol.696 No.1

INFLATION , TAXATION , AND THE INTERNATIONAL ALLOCATION OF CAPITAL

WONG, DAVID Y. 한국국제경제학회 1989 International Economic Journal Vol.3 No.1

This paper examines the interactive effects of inflation and taxation on the international allocation of capital using an open-economy monetary growth model. The joint effects of inflation and taxation on international capital flows, the economy-wide debt-equity ratio, and the various balance of payments accounts are explicitly modeled. Elements of the analysis include the important issue of investment finance, and integrated tax structure, and depreciation accounting. It is found that inflation weakens the current account position. Also, the effects of inflation on capital intensity are, in general, sensitive to the method of investment finance.

Crystallinity Effects on the heat Distortion Temperature (HDT) of Semi-crystalline Polymers

Wong, A . C . Y .,Ng, N . S . K . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.3

Three semi-crystalline polymers were carefully injection moulded with different mould cooling temperatures for the investigation of crystallinity effects on the heat distortion tempetature (HDT). It was found that the HDT of PP was more affected by the cooling temperature than LDPE and HDPE. In addition, for PP a linear correlation was found to exist between the HDT and T_(mould). It was also demonstrated that rate of deflection and range of temperature within which continuous deflection took place were also affected by the cooling temperature. The findings are believed of practical significance for product design.

Party Competition and Ideology in Hong Kong: A New Manifesto Coding Dataset

Mathew Y. H. Wong 동아시아연구원 2020 Journal of East Asian Studies Vol.20 No.2

This study provides a new dataset on the ideological positions of political parties in Hong Kong, which is a hybrid regime with electoral elements. Using this dataset, the study challenges the non-ideological view of party competition in Hong Kong by identifying an ideological dimension to the elections held between 1998 and 2016. It is shown that parties do position themselves along an identifiable left–right spectrum, with shifts that can be meaningfully interpreted, and that the aggregate ideology of the electorate appears to be linked to the level of economic growth. The ideological dimension provides a novel perspective on local politics that looks beyond the dominant pro-democracy versus pro-Beijing divide while also shedding light on the recent changes underlying the latter. This study provides valuable objective data for analyzing political competition dynamics and contributes to the comparative literature by incorporating Hong Kong into the framework of the manifesto coding project.

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.