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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.
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Wong, K.L.,Chuan, M.W.,Chong, W.K.,Alias, N.E.,Hamzah, A.,Lim, C.S.,Tan, M.L.P. Techno-Press 2019 Advances in nano research Vol.7 No.3
Graphene, with impressive electronic properties, have high potential in the microelectronic field. However, graphene itself is a zero bandgap material which is not suitable for digital logic gates and its application. Thus, much focus is on graphene nanoribbons (GNRs) that are narrow strips of graphene. During GNRs fabrication process, the occurrence of defects that ultimately change electronic properties of graphene is difficult to avoid. The modelling of GNRs with defects is crucial to study the non-idealities effects. In this work, nearest-neighbor tight-binding (TB) model for GNRs is presented with three main simplifying assumptions. They are utilization of basis function, Hamiltonian operator discretization and plane wave approximation. Two major edges of GNRs, armchair-edged GNRs (AGNRs) and zigzag-edged GNRs (ZGNRs) are explored. With single vacancy (SV) defects, the components within the Hamiltonian operator are transformed due to the disappearance of tight-binding energies around the missing carbon atoms in GNRs. The size of the lattices namely width and length are varied and studied. Non-equilibrium Green's function (NEGF) formalism is employed to obtain the electronics structure namely band structure and density of states (DOS) and all simulation is implemented in MATLAB. The band structure and DOS plot are then compared between pristine and defected GNRs under varying length and width of GNRs. It is revealed that there are clear distinctions between band structure, numerical DOS and Green's function DOS of pristine and defective GNRs.
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Wong Joanna K. L.,Ke Yuhe,Ong Yi Jing,Li HuiHua,Wong Ting Hway,Abdullah Hairil Rizal 대한마취통증의학회 2022 Korean Journal of Anesthesiology Vol.75 No.1
Background: Diabetes is a risk factor for postoperative complications. Previous meta-analyses have shown that elevated glycated hemoglobin (HbA1c) levels are associated with postoperative complications in various surgical populations. However, this is the first meta-analysis to investigate the association between preoperative HbA1c levels and postoperative complications in patients undergoing elective major abdominal surgery.Methods: PRISMA guidelines were adhered to for this study. Six databases were searched up to April 1, 2020. Primary studies investigating the effect of HbA1c levels on postoperative complications after elective major abdominal surgery were included. Risk of bias and quality of evidence assessments were performed. Data were pooled using a random effects model. Meta-regression was performed to evaluate different HbA1c cut-off values. Results: Twelve observational studies (25,036 patients) were included. Most studies received a ‘good’ and ‘moderate quality’ score using the NOS and GRADE, respectively. Patients with a high HbA1c had a greater risk of anastomotic leaks (odds ratio [OR]: 2.80, 95% CI [1.63, 4.83], P < 0.001), wound infections (OR: 1.21, 95% CI [1.08, 1.36], P = 0.001), major complications defined as Clavien-Dindo [CD] 3–5 (OR: 2.16, 95% CI [1.54, 3.01], P < 0.001), and overall complications defined as CD 1–5 (OR: 2.12, 95% CI [1.48, 3.04], P < 0.001).Conclusions: An HbA1c between 6% and 7% is associated with higher risks of anastomotic leaks, wound infections, major complications, and overall postoperative complications. Therefore, guidelines with an HbA1c threshold > 7% may be putting pre-optimized patients at risk. Future randomized controlled trials are needed to explore causation before policy changes are made.
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The Efficacy of Herbal Supplement Danggui Buxue Tang for Relieving Menopausal Symptoms
( Eliza L. Y. Wong ),( Annie W. L. Cheung ),( C. J. Haines ),( C. C. Wang ),( Chun-kwok Wong ),( Karl W. K. Tsim ),( William K. F. Cheng ),( Ping-chung Leung ) 대한폐경학회 2022 대한폐경학회지 Vol.28 No.1
Objectives: This study aimed to further explore the efficacy and safety of Danggui Buxue Tang (DBT), a simple herbal formula, for improving the quality of life of women suffering from menopausal symptoms. Methods: A third clinical trial to determine the clinical efficacy of high-dose DBT for a period of 12 weeks was carried out. The standard Menopause-Specific Quality of Life (MENQOL) assessment chart was used for the evaluation. Safety was defined as an absence of direct estrogenic effects, serum inflammatory cytokines. Notably, interleukin IL-6, IL-8 and tumor necrosis factor TNF-α, known to be directly related to estrogenic reactions in menopause studies, were monitored. Results: The third clinical trial indicated an overall improvement in the four domains of MENQOL, offering further proof of the efficacy of DBT demonstrated in the two previous trials. The serial checks of the three cytokines related to estrogen activities did not show either upward or downward trends. The haphazard behavior reactions of the three cytokines offered indirect indications that DBT improved the MENQOL independently from estrogen activities. Conclusions: The three clinical trials using DBT to relieve menopausal syndrome have offered solid evidence for its efficacy. The uncertainty regarding whether the “phytoestrogen” contained in DBT had bioactivities similar to estrogen was alleviated through the confirmation that no strict estrogenic bioactivities were observed. The issue of safety was further clarified via laboratory platform studies on DBT, which not only showed the lack of similarity with estrogen actions but also confirmed the value of combining the two herbs in the classic formula.
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Joyce L.C. Ma,Timothy K.Y. Wong,Y.K. Lau,Lauren L.Y. Lai 한국사회복지학회 2011 Asian Social Work and Policy Review Vol.5 No.3
This article reports the results of a telephone survey (n = 1002) conducted in November 2008,which aimed to identify parenting stress and perceived family functioning of Chinese parents inHong Kong; to explore the effects of the parents’ socio-demographic characteristics (gender, familyincome, education and family structure) on the aforementioned stress and functioning variables;and to examine the interrelationship among these characteristics and the two variables in question. Results showed that the reported parenting stress was at average level, while the perceived familyfunctioning was slightly below average. The results also indicated that the parenting stress of mothers,single parents, the low-income and the less-educated was higher than that of fathers, parents ofnuclear and extended families, the high-income and the better-educated. Socio-demographic characteristicsexcept the parent’s gender had similar effects on perceived family functioning. Higherparenting stress was associated with lower family functioning, and explained a larger variancein the perceived family functioning than the socio-demographic characteristics taken alone. The results of the study have provided empirical support regarding the interrelationships amongthe vulnerable groups in society, parenting stress and perceived family functioning. Implicationsof the study for social work practice are discussed.
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Ma, K.K.,Chau, Wai Wang,Wong, Connie H.N.,Wong, Kerry,Fung, Nicholas,Lee, J.T. Andrea,Choi, L.Y. Catherine,Suen, Dacita T.K.,Kwong, Ava Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.5
Background: Ethnic variation in tumor characteristics and clinical presentation of breast cancer is increasingly being emphasized. We studied the tumor characteristics and factors which may influence the presentation and prognosis of triple negative breast cancers (TNC) in a cohort of Chinese women. Methods: A prospective cohort of 1800 Chinese women with breast cancer was recruited in a tertiary referral unit in Hong Kong between 1995 and 2006 and was followed up with a median duration of 7.2 years. Of the total, 216 (12.0%) had TNC and 1584 (88.0%) had non-TNC. Their clinicopathological variables, epidemiological variables and clinical outcomes were evaluated. Results: Patients with TNC had similar age of presentation as those with non-TNC, while presenting at earlier stages (82.4% were stage 1-2, compared to 78.4% in non-TNC, p=0.035). They were likely to be associated with grade 3 cancer (Hazard Ratio(HR)=5.8, p<0.001). TNC showed higher chance of visceral relapse (HR=2.69, p<0.001), liver metastasis (HR=1.7, p=0.003) and brain metastasis (HR=1.8, p=0.003). Compared with non-TNC group, TNC had similar 10-year disease-free survival (82% vs 84%, p=0.148), overall survival (78% vs 79%, p=0.238) and breast cancer-specific mortality (18% vs 16%, p=0.095). However, TNC showed poorer 10-year stage 3 and 4 specific survival (stage 3: 53% vs. 67%, p=0.010; stage 4: 0% vs. 40%, p=0.035). Conclusions: Chinese women with triple negative breast cancer do not have less aggressive biological behavior compared to the West and presentation at a later stage results in worse prognosis compared with those with non triple negative breast cancer.
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Field measurement results of Tsing Ma suspension Bridge during Typhoon Victor
Xu, Y.L.,Zhu, L.D.,Wong, K.Y.,Chan, K.W.Y. Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.10 No.6
A Wind and Structural Health Monitoring System (WASHMS) has been installed in the Tsing Ma suspension Bridge in Hong Kong with one of the objectives being the verification of analytical processes used in wind-resistant design. On 2 August 1997, Typhoon Victor just crossed over the Bridge and the WASHMS timely recorded both wind and structural response. The measurement data are analysed in this paper to obtain the mean wind speed, mean wind direction, mean wind inclination, turbulence intensity, integral scale, gust factor, wind spectrum, and the acceleration response and natural frequency of the Bridge. It is found that some features of wind structure and bridge response are difficult to be considered in the currently used analytical process for predicting buffeting response of long suspension bridges, for the Bridge is surrounded by a complex topography and the wind direction of Typhoon Victor changes during its crossing. It seems to be necessary to improve the prediction model so that a reasonable comparison can be performed between the measurement and prediction for long suspension bridges in typhoon prone regions.
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Ambient Vibration measurements and finite element modelling for the Hong Kong Ting Kau Bridge
Au, F.T.K.,Tham, L.G.,Lee, P.K.K.,Su, C.,Han, D.J.,Yan, Q.S.,Wong, K.Y. Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.15 No.1
The Ting Kau Bridge in Hong Kong is a cable-stayed bridge comprising two main spans and two side spans. The bridge deck is supported by three towers, an end pier and an abutment. Each of the three towers consists of a single reinforced concrete mast which reduces its section in steps, and it is strengthened by transverse cables and struts in the transverse vertical plane. The bridge deck is supported by four inclined planes of cables emanating from anchorages at the tower tops. In view of the threat from typhoons, the dynamic behaviour of long-span cable-supported bridges in the region is always an important consideration in their design. This paper is devoted to the ambient vibration measurements of the bridge for evaluation of dynamic characteristics including the natural frequencies and mode shapes. It also describes the modelling of the bridge. A few finite element models are developed and calibrated to match with the field data and the results of subsequent structural health monitoring of the bridge.
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