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Comparative studies on Zn_(0.95)Co_(0.05)O thin films on C- and R-sapphire substrates

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Chinese Physics B 2009年第12期18卷 5501-5506页

作者：彭英姿 Thomas liew Song Wen-Dong Chong Tow Chong Data Storage Instit u re DSI Building 5 Engineering Drive 1 Singapore 117608 Electrical and Computer Engineering Department National University of Singapore Singapore 119260 School of Science Hangzhou Dianzi University Hangzhou 310018 China

Zn0.95Co0.05O precipitate-free single crystal thin films were synthesized by a dual beam pulsed laser deposition method. The films form a wurtzite structure whose hexagonal axis is perpendicular or parallel to the plane of the surface depending on the C-plane （0001） or R-plane （1120） sapphire substrate. Based on the results of high-resolution transmission electron microscopy and x-ray diffraction, C-plane films show larger lattice mismatch. The films exhibit magnetic and semiconductor properties at room temperature. The coercivity of the film is about 8000 A/m at room temperature. They are soft magnetic materials with small remanent squareness S for both crystal orientations. There is no evidence to show that the anisotropy is fixed to the hexagonal axis （C-axis） for the wurtzite structure.

关键词： Co-doped ZnO thin films diluted magnetic semiconductor anisotropy

OPTICAL BAND GAP AND CONDUCTIVITy.m.ASUREmENTS OF POLyPyRROLE-CHITOSAN COmPOSITE THIN FILmS

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Chinese Journal of Polymer Science 2012年第1期30卷 93-100页

作者： mahnaz m.Abdi H.N.m.Ekramul mahmud Luqman Chuah Abdullah Anuar Kassim mohamad Zaki Ab.Rahman Josephine liew ying Chyi Laboratory of Biopolymer and Derivatives Institute of Tropical Forestry and Forest Products(INTROP) Universiti Putra Malaysia43400 SerdangSelangorMalaysia Department of Chemistry Faculty of Science University of Malaya50603Kuala LumpurMalaysia Department of Chemistry Faculty of Science Universiti Putra Malaysia43400 SerdangSelangorMalaysia Department of Physics Faculty of Science Universiti Putra Malaysia43400 SerdangSelangorMalaysia

Electrical conductivity and optical properties of polypyrrole-chitosan（PPy-CHI） conducting polymer composites have been investigated to determine the optical transition characteristics and energy band gap of composite *** two electrode method and I-V characteristic technique were used to measure the conductivity of the PPy-CHI thin films,and the optical band gap was obtained from their ultraviolet absorption *** upon experimental parameter,the optical band gap（E_g） was found within 1.30-2.32 eV as estimated from optical absorption *** band gap of the composite films decreased as the CHI content *** room temperature electrical conductivity of PPy-CHI thin films was found in the range of 5.84×10^（-7）-15.25×10^（-7） S·cm^（-1） depending on the chitosan *** thermogravimetry analysis（TGA） showed that the CHI can improve the thermal stability of PPy-CHI composite films.

关键词： Polymer composite Electron transition I-V characteristic technique Optical band gap Polypyrrole

Analysis of magnetic mechanisms of 3d-doped ZnO diluted magnetic semiconductors by an abnormal peak on m-T curve

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Chinese Science Bulletin 2007年第20期52卷 2742-2746页

作者： PENG yingZi THOmAS liew yE ZhiZhen ZHANG yinZhu nstitute of materials and Physics School of Science Hangzhou Dianzi University Hangzhou 310018 China Data Storage Institute DSI Building 5 Engineering Drive 1 Singapore 117608 Singapore Department of Electrical and Computer Engineering National University of Singapore 119260 Singapore State Key Lab of Silicon materials Zhejiang University Hangzhou 310027 China

The crystallographic structures and magnetic properties of a Zn0.95Co0.05O thin film deposited on a C-sapphire substrate using a dual-beam pulsed laser deposition method were characterized. It was shown from crystallographic analysis that the film belongs to the wurtzite structure with the C-axis aligned with that of the substrate. magnetic hysteresis loops were observed till up to room temperature. A small peak around 55 K was noticed on the magnetization vs. temperature curve. The corresponding temperature of the small peak is close to that of ‘the abnormal peak’ reported by X.m. Zhang et al. From the results obtained, no correlation was found between the abnormal peak and the quantum effects. The magnetic behaviors in the Zn0.95Co0.05O film cannot be explained by the ferromagnetism in diluted magnetic semiconductors. The magnetic mechanisms in ZnO-based diluted magnetic semiconductors are also discussed.

关键词：弱磁半导体抗磁性氧化锌性能

Role of the CXCR4-SDF1-HmGB1 pathway in the directional migration of cells and regeneration of affected organs

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World Journal of Stem Cells 2020年第9期12卷 938-951页

作者： Nazmul Haque Ismail m Fareez liew Fong Fong Chanchal mandal Noor Hayaty Abu Kasim Kranthi RajaKacharaju Pratiwi Soesilawati Department of Oral Biology and Biomedical Sciences Faculty of DentistryMAHSA UniversitySelangor 42610Malaysia Biotechnology and Genetic Engineering Discipline Life ScienceKhulna UniversityKhulna 9208Bangladesh Faculty of Dentistry University Kebangsaan MalaysiaKuala Lumpur 50300Malaysia Faculty of Dental medicine Universitas AirlanggaSurabaya 411007Indonesia Department of Conservative Dentistry Faculty of Dentistry MAHSA UniversitySelangor 42610Malaysia Department of Oral Biology Faculty of Dental MedicineUniversitas AirlanggaSurabaya 60115Indonesia

In recent years,several studies have reported positive outcomes of cell-based therapies despite insufficient engraftment of transplanted *** findings have created a huge interest in the regenerative potential of paracrine factors released from transplanted stem or progenitor ***,this notion has also led scientists to question the role of proteins in the secretome produced by cells,tissues or organisms under certain conditions or at a particular time of regenerative *** studies have revealed that the secretomes derived from different cell types contain paracrine factors that could help to prevent apoptosis and induce proliferation of cells residing within the tissues of affected *** could also facilitate the migration of immune,progenitor and stem cells within the body to the site of *** these different paracrine factors present within the secretome,researchers have given proper consideration to stromal cell-derived factor-1(SDF1)that plays a vital role in tissue-specific migration of the cells needed for *** researchers recognized that SDF1 could facilitate site-specific migration of cells by regulating SDF1-CXCR4 and/or HmGB1-SDF1-CXCR4 pathways which is vital for tissue *** in this study,we have attempted to describe the role of different types of cells within the body in facilitating regeneration while emphasizing the HmGB1-SDF1-CXCR4 pathway that orchestrates the migration of cells to the site where regeneration is needed.

关键词： C-X-C motif chemokine 12 mesenchymal stem cells monocytes Neutrophils Peripheral blood mononuclear cells Receptor for advanced glycation end products

Six novel species of Fusarium from natural ecosystems in Australia

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Fungal Diversity 2016年第2期77卷 349-366页

作者： m.H.Laurence J.L.Walsh L.A.Shuttleworth D.m.Robinson R.m.Johansen T.Petrovic T.T.H.Vu L.W.Burgess B.A.Summerell E.C.y.liew The Royal Botanic Gardens and Domain Trust Mrs Macquaries RdSydneyNSW 2000Australia Faculty of Agriculture and Environment The University of SydneyEveleighNSW 2015Australia

Six new species of Fusarium associated with soil and plant hosts from ecosystems of minimal anthropogenic disturbance in Australia are *** coicis from Coix gasteenii,*** from Xanthorrhoea glauca,*** from soil and mangifera indica,*** from soil,*** from Sorghum interjectum and *** from soil,Triodia microstachya,Sorghum interjectum and Sorghum *** and phylogenetic analysis of EF-1α,RPB1 and RPB2 sequence data were used to delineate species *** new species were phylogenetically distributed in the Fusarium sambucinum,***,and *** species complexes,and two novel species *** six new species have particular phylogeographic significance as not only do they provide further insight into the geographic patterns of Fusarium evolution but also challenge current phylogeographic hypotheses.

关键词： Species diversity Endophyte Phylogenetics mycoflora Phylogeography

multi-scale mechanics and materials modeling

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Multi-scale Mechanics and Materials Modeling

64-row multi-dector computed tomography coronary image from a center with early experience: first illustration of learning curve

第十一届南方计算力学学术会议（SCCm-11）

作者： K.m.liew Department of Architecture and Civil Engineering City University of Hong Kong

multi-scale methods have been used to model complex materials systems to understand their mechanical behaviors across multiple length scales. multi-scale modeling enables us to design smarter, multi-functional, and better sustainable structural systems. This talk will focus on several reseach works which were done in recent years in multi-scale mechanics and materials modeling. To solve a mechanical problem, theoretical, computational or experimental techniques can be used. While there is a trend towards interaction among these different techniques, curently is very limited. Because of the extremely small size in micro-and nano-structures, experimental studies are generally quite difficult. Although experimental studies can capture certain phenomena, it is impossible to understand their delicate properties well through experimental investigations alone. In addition to a large amount of experimental works, theoretical analysis and numerical modeling play important roles in capturing the delicate behavior of complex materials systems. Theoretical and numerical approaches can be generally classified into two categories: microscale method and macroscale method. A microscale method can capture the microscale mechanism of micro-and nano-structures and yield results which are in many cases explicit in nature. However, a microscale method may consume a large amount of computational resources, thus computation can carry out on a very small size domain. This huge computational limitation likely restricts their application. A macroscale continuum simulation can largely reduce the degrees of freedom in a problem, and the theoretical and numerical analyses of large-size structures thus become possible. However, a continuum simulation cannot reflect the microscale physical laws, and is inadequate. The limitations of the microscale method as well as the macroscale method have motivated extensive research into the multi-scale method that couples the microscale method and the contin

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Journal of Geriatric Cardiology 2006年第1期3卷 29-34页

作者： Sze Piaw CHIN Tiong Kiam ONG Chee Khoon liew m.Tobias Seyfarth Fong yean yip ALAN Houng Bang liew Kui Hian SIm Dept of Cardiology Sarawak General Hospital Siemens Cardiac Solutions Erlangen Germany

Background and objectives The recent joint ACCF/AHA clinical competence statement on cardiac imaging with multi-detector computed tomography recommended a minimum of 6 months training and 300 contrast examinations, of which the candidate must be directly involved in at least 100 studies. Whether this is adequate to become proficient in interpretation of coronary computed tomogsignificant coronary stenosis in a center with 1 year's experience using a 64-row scanner. methods A total of 778 patients underwent contrast-enhanced CTA between January and December 2005. Out of these patients, 301 patients also underwent contrast-enhanced conventional coronary angiography (CCA). These patients were divided into 4 groups according to the time the examination was underwent. Group Q1: first quarter of the year (n=20), Group Q2: second quarter (n=128), Group Q3: third quarter (n=134), and Group Results The sensitivity, specificity, positive, and negative predictive values were Q1 - 64%, 89%, 49% and 94%, respectively; Q2 -79%, 96%, 74% and 97%, respectively; Q3 - 78%, 96%, 74%, 97%, respectively, and Q4 - 100% for all. Conclusions In a center with formal training and high caseload, our accuracy in CTA analysis reached a plateau after 6 months experience. Test-bolus protocols produce better image quality and can improve accuracy. New centers embarking on CTA will need to overcome an initial 6-month learning curve depending upon the caseload during which time they should consider correlation with CCA.

关键词： computed tomography training angiography coronary artery disease

Elastic Bending Analysis of Folded Plates and Plate Structures Using the meshfree Galerkin method

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Elastic Bending Analysis of Folded Plates and Plate Structur...

High-resolution computed tomography in patients with atypical 'cardiac' chest pain: a study investigating patients at 10-year cardiovascular risks defined by the Framingham and PROCAm scores

第一届工程科学与力学中的计算方法国际会议

作者： K.m.liew S.Kitipornchai Department of Building and Construction City University of Hong KongHong KongChina Department of Building and Construction City University of Hong KongHong KongChina

＜正＞A meshfree Galerkin method that is based on the first-order shear deformation theory （FSDT） is introduced to investigate the elastic bending behaviors of stiffened and un-stiffened folded plates under different loadings and boundary conditions. Folded plates are regarded as assemblies of flat plates that lie in different planes. The stiffness matrices of the flat plates are given by the meshfree Galerkin method. Employing the element concept, which is borrowed from the finite element method, and treating every flat plate as a super element, the global stiffness matrix of the entire folded plate is obtained by superposing the stiffness matrices of the flat plates. This is about the same for the analysis of stiffened folded plates. They are considered as assemblies of stiffened flat plates. The stiffness matrices of the stiffened plates are also given by the meshfree method. Unlike the finite element methods, no mesh is required in determining the stiffness matrices for the flat plates and the stiffened plates in this paper, which means time-consuming remeshing is entirely avoided for problems such as stiffener position changes of stiffened folded plates. To demonstrate the accuracy and convergence of the method, several numerical examples are calculated by it and the finite element commercial software ANSyS. Good agreement is observed between the two sets of results.

关键词： mesh-free Galerkin method meshless folded plate stiffened plate bending

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Journal of Geriatric Cardiology 2006年第1期3卷 17-21页

作者： Choon Kiat ANG Alan yean yip FONG Sze Piaw CHIN Tiong Kiam ONG Seyfarth m Tobias Chee Khoon liew Rapaee ANNUAR Houng Bang liew Kui Hian SIm Deptartment of Cardiology Sarawak General Hospital Sarawak Malaysia Siemens medical Solutions Germany Deptartment of Cardiology Sarawak General Hospital SarawakMalaysia University.m.laysia Sarawak malaysia

Background and objective Atypical 'cardiac' chest pain (ACCP) is not usually caused by.m.ocardial ischaemia. Current noninvasive investigations for these symptoms are not yet as accurate as invasive coronary angiography. The latest 64-row multi-detector computed tomography (mDCT) technology is non-invasive, has high specificity and negative predictive values for the detection of significant coronary disease. Our aim was to investigate if this modality can provide more information in the assessment of outpatients with ACCP in addition to established cardiovascular risk scores. methods Seventy consecutive patients presenting to the outpatient clinic with ACCP underwent 64-row mDCT scan of the coronary arteries. They were categorized into low, medium or high risk groups based upon the Framingham and PROCAm scores. We defined a clinically abnormal mDCT scan as coronary stenosis =50% or calcium score ＞400 Agatston. Results Fifty-three (75.7%) patients did not have clinically abnormal scans. Framingham score classified 43 patients as low-risk while PROCAm classified 59 patients as low-risk. mDCT scans were abnormal for 18.6% and 22.0% of the respective low-risk group of patients. For patients with medium-to-high risk, 33.3% and 36.4% of Framingham and PROCAm patient groups respectively had abnormal mDCT scans. Conclusion mDCT adds valuable information in the assessment of patients with ACCP by identifying a significant proportion of patients categorized as low-risk to have underlying significant coronary stenosis and coronary calcification by established cardiovascular risk scores.

关键词： multi-detector computed tomography atypical 'cardiac' chest pain coronary artery disease risk stratification