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Potential Use of Strain Hardening ECC in Permanent Formwork with Small Scale Flexural Beams

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Journal of Wuhan University of Technology(Materials Science) 2009年第3期24卷 482-487页

作者：李贺东 christopher K Y leung Department of Civil Engineering Hong Kong University of Science and Technology

Utilizing pre-cast ECC panels as participating permanent formwork of concrete members, and the validity of using ECC to disperse the single crack in concrete into multiple ones in ECC were studied. In the process, totally two kinds of ECC with different tensile properties, 7 series of flat panels with different top surface figures and 3 U-shape panels with different inner surface forms were investigated. To evaluate the performance of the permanent formworks, small ECC-concrete composite beams were cast and tested mechanically. The 4-point bending test results show that the use of pre-cast ECC panels as permanent formwork can significantly improve the load capacity and toughness of a concrete member, effectively dispersing single widely opened crack in concrete into multiple ones in ECC. Most permanent formworks show perfect bond with the concrete cast on them, while the ones with partially debonded zone achieve the best mechanical performance. The U-shape permanent formworks show better performances than the flat ones, achieving much betler improvements in both the load capacity and toughness, together with better crack width control.

关键词： pseudo strain hardening cementitious composites permanent formwork toughness crack

Experimental study on mechanical behaviors of pseudo-ductile cementitious composites under biaxial compression

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Science China(Technological Sciences) 2013年第4期56卷 963-969页

作者： ZHOU JiaJia PAN JinLong leung christopher Kin Ying LI ZongJin Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education Southeast University Department of Civil and Environmental Engineering Hong Kong University of Science and Technology

Experimental investigation was conducted to characterize the responses of pseudo-ductile cementitious composites (PDCCs) when subjected to uniaxial and biaxial *** PDCCs is a class of fiber reinforced cementitious composites with ultra-high ductility by using a low volume fraction (2%) of polyvinyl alcohol (PVA) *** different strength grades of PDCC were examined with cubic specimen size of 100 mm in the *** specimens were loaded with a servo-hydraulic jack at different stress *** principle stresses and strains of the specimens were recorded,and the failure modes with various stress states were *** test results indicated that the ultimate strength of PDCCs increased due to the lateral confinement in the other principal stress direction,and the maximum ultimate strength occurred at the biaxial stress ratio of 0.25,which was very different from common concrete *** the PDCC specimens,the biaxial strength may be lower than the uniaxial strength when subjected to biaxial compression with the stress ratio of 1.0,and the failure mode showed a shear-type failure because of the bridging effect of ***,a failure criterion was proposed for PDCCs under biaxial compression.

关键词： PDCC biaxial strength stress-strain curve failure mode failure criterion

Experimental study on mechanical behavior of high performance concrete under multi-axial compressive stress

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Science China(Technological Sciences) 2014年第12期57卷 2514-2522页

作者： ZHOU Jia Jia PAN Jin Long leung christopher Kin Ying LI Zong Jin Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education Southeast University Department of Civil and Environmental Engineering Hong Kong University of Science and Technology

Experimental investigation was conducted to characterize the responses of high performance concrete(HPC) subjected to multiaxial compressive stresses. The HPC specimens were prepared with three different mix proportions, which corresponds to three different uniaxial compressive strengths. The cubic specimens with size of 100 mm for each edge were tested with servo-hydraulic actuators at different stress ratios. The principal stresses and strains of the specimens were recorded, and the failure of the cubic specimens under various stress states was examined. The experimental results indicated that the stress states and stress ratios had significant influence on the strength and deformation of HPC under biaxial and triaxial compression, especially under triaxial compression. Failure criteria were proposed for the HPC specimens under biaxial and triaxial compressive loading. The test results provided a valuable reference for obtaining multi-axial constitutive law for HPC.

关键词： high performance concrete (HPC) biaxial compressive stress triaxial compressive stress failure criterion stress-straincurve

埋入光纤Mach-Zehnder干涉仪检测复合材料梁的分层

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复合材料学报 2004年第1期21卷 129-133页

作者：江毅许颖 christopher K Y leung 北京理工大学光电工程系北京100081 香港科技大学土木工程系

　将光纤Mach-Zehnder干涉仪的传感臂埋入到复合材料梁的中性层来检测梁的分层。不论梁是连续支撑还是简单支撑,均取得了很好的实验结果。通过用榔头连续下压梁,由光纤干涉仪可以得到一条输出曲线,从这条曲线就可以准确判断梁内部是否... 详细信息

　将光纤Mach-Zehnder干涉仪的传感臂埋入到复合材料梁的中性层来检测梁的分层。不论梁是连续支撑还是简单支撑,均取得了很好的实验结果。通过用榔头连续下压梁,由光纤干涉仪可以得到一条输出曲线,从这条曲线就可以准确判断梁内部是否存在分层,以及分层的位置。

关键词：复合材料分层光纤传感器 Mach-Zehnder干涉仪

Adaptive optics two-photon microscopy enables near-diffraction-limited and functional retinal imaging in vivo

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Light(Science & Applications) 2020年第1期9卷 1298-1308页

作者： Zhongya Qin Sicong He Chao Yang Jasmine Sum-Yee Yung Congping Chen christopher Kai-Shun leung Kai Liu Jianan Y.Qu Department of Electronic and Computer Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina Division of Life Science The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina Department of Ophthalmology and Visual Sciences The Chinese University of Hong KongHong KongChina State Key Laboratory of Molecular Neuroscience The Hong Kong University of Science and TechnologyClear Water BayKowloonHongKongChina Center of Systems Biology and Human Health The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina

In vivo fundus imaging offers non-invasive access to neuron structures and biochemical processes in the ***,optical aberrations of the eye degrade the imaging resolution and prevent visualization of subcellular retinal *** developed an adaptive optics two-photon excitation fluorescence microscopy(AO-TPEFM)system to correct ocular aberrations based on a nonlinear fluorescent guide star and achieved subcellular resolution for in vivo fluorescence imaging of the mouse *** accurate wavefront sensing and rapid aberration correction,AOTPEFM permits structural and functional imaging of the mouse retina with submicron ***,simultaneous functional calcium imaging of neuronal somas and dendrites was ***,the timelapse morphological alteration and dynamics of microglia were characterized in a mouse model of retinal *** addition,precise laser axotomy was achieved,and degeneration of retinal nerve fibres was *** highresolution AO-TPEFM is a promising tool for non-invasive retinal imaging and can facilitate the understanding of a variety of eye diseases as well as neurodegenerative disorders in the central nervous system.

关键词： optics functional photon

Glial cells and glaucomatous neuropathy

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Chinese Medical Journal 2007年第4期120卷 326-335页

作者： ZHONG Yi-sheng christopher Kai-shun leung Chi-pui Pang Department of Ophthalmology Ruijin Hospital Shanghai JiaotongUniversity Shanghai 200025 China Department of-Ophthalmology and Visual Sciences ChineseUniversity of Hong Kong Hong Kong China

Glaucomatous optic neuropathy is characterized by progressive loss of retinal ganglion cells associated with visual functional deficits. As the ganglion cells die in glaucoma, there is a progressive thinning of the nerve fibre layer （NFL）.l The underlying pathophysiological mechanisms, however, remain unclear. Many mechanisms are involved in the initiation and process of irreversible ganglionic cell death in glaucoma. These include reduced axoplasmic transport, accumulation of toxic levels of neurotransmitter, increased nitric oxide and endothelin syntheses, and remodelling of the extracellular matrix, among others.

关键词：内皮缩血管肽类青光眼神经递质药神经胶质视神经疾病视网膜神经节细胞细胞死亡胰岛素

Dietary advanced glycation end-products aggravate non-alcoholic fatty liver disease

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World Journal of Gastroenterology 2016年第35期22卷 8026-8040页

作者： christopher leung Chandana B Herath Zhiyuan Jia Sof Andrikopoulos Bronwyn E Brown Michael J Davies Leni R Rivera John B Furness Josephine M Forbes Peter W Angus Department of Medicine the University of MelbourneAustin HealthHeidelbergMelbourne Victoria 3084Australia Department of Gastroenterology and Hepatology Austin HealthAustin HospitalHeidelberg MelbourneVictoria 3084 Australia Heart Research Institute Newtown New South Wales 2042Austrulia University of Melbourne Victoria 3052Australia Metabolic Research Unit School of MedicineDeakin UniversityVictoria 3216Austrialia Glycation and Diabetes Complications Group Mater Medical Research InstituteSouth BrisbaneQueensland 4101Australia

AIM To determine if manipulation of dietary advanced glycation end product(AGE), intake affects nonalcoholic fatty liver disease(NAFLD) progression and whether these effects are mediated via RAGE. METHODS Male C57Bl6 mice were fed a high fat, high fructose, high cholesterol(HFHC) diet for 33 wk and compared with animals on normal chow. A third group were given a HFHC diet that was high in AGEs. Another group was given a HFHC diet that was marinated in vinegar to prevent the formation of AGEs. In a second experiment, RAGE KO animals were fed a HFHC diet or a high AGE HFHC diet and compared with wildtype controls. Hepatic biochemistry, histology, picrosirius red morphometry and hepatic mR NA were determined. RESULTS Long-term consumption of the HFHC diet generated significant steatohepatitis and fibrosis after 33 wk. In this model, hepatic 4-hydroxynonenal content(a marker of chronic oxidative stress), hepatocyte ballooning, picrosirius red staining, α-smooth muscle actin and collagen type 1A gene expression were all significantly increased. Increasing the AGE content of the HFHC diet by baking further increased these markers of liver damage, but this was abrogated by pre-marination in acetic acid. In response to the HFHC diet, RAGE-/-animals developed NASH of similar severity to RAGE+/+ animals but were protected from the additional harmful effects of the high AGE containing diet. Studies in isolated Kupffer cells showed that AGEs increase cell proliferation and oxidative stress, providing a likely mechanism through which these compounds contribute to liver injury. CONCLUSION In the HFHC model of NAFLD, manipulation of dietary AGEs modulates liver injury, inflammation, and liver fibrosis via a RAGE dependent pathway. This suggests that pharmacological and dietary strategies targeting the AGE/RAGE pathway could slow the progression of NAFLD.

关键词： Advanced glycation end-products Fructose Steatohepatitis Non-alcoholic fatty liver disease Hepatic fibrosis Oxidative stress

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高延性水泥基复合材料的制备技术综述

河北工业大学学报 2014年第6期43卷 17-21页

作者：庞超明 leung christopher K Y 孙伟东南大学材料科学与工程学院江苏省土木工程材料重点实验室江苏南京211189 香港科技大学土木工程与环境学院

高延性水泥基复合材料(HDCC)是一种具有应变硬化、多缝开裂和高延性等特性的纤维增强水泥基复合材料.从HDCC材料的设计理论、材料选择、配合比设计、养护等方面综述了HDCC材料的制备技术,分析了制备HDCC时易忽略的几个关键技术,提出了H... 详细信息

高延性水泥基复合材料(HDCC)是一种具有应变硬化、多缝开裂和高延性等特性的纤维增强水泥基复合材料.从HDCC材料的设计理论、材料选择、配合比设计、养护等方面综述了HDCC材料的制备技术,分析了制备HDCC时易忽略的几个关键技术,提出了HDCC的制备方法.明确了提高HDCC强度、抗渗性及与之相关耐久性的难度,提出HDCC的制备时,要注意基体强度与断裂韧度发展规律的差异,减少大颗粒材料等提高基体本身及纤维分布的均匀性,制备时可采用使用高掺量低活性粉煤灰,橡胶微粉和EVA乳胶粉、较高水胶比、较高胶砂比、减少养护等降低基体的断裂韧度的措施.基于现有HDCC设计理论及制备技术,要大幅度提高强度和耐久性,选择更匹配的纤维或调整优化纤维性能至关重要.

关键词：高延性纤维增强水泥基复合材料制备技术断裂韧度

用光纤干涉仪检测I形复合材料梁腹板/翼缘连接处的分层

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复合材料学报 2007年第2期24卷 143-150页

作者：许颖梁坚凝江毅深圳市建筑科学研究院香港科技大学土木工程系北京理工大学光电工程系北京100081

介绍了一种在超声回弹波频谱分析基础上用光纤干涉仪来检测I形复合材料梁腹板/翼缘连接处分层的方法,利用超声发射器在I形梁中产生应力波,用表面粘贴的光纤干涉仪来接收应力波产生的输出信号,对此信号进行频谱分析可找到I形梁的分层位... 详细信息

介绍了一种在超声回弹波频谱分析基础上用光纤干涉仪来检测I形复合材料梁腹板/翼缘连接处分层的方法,利用超声发射器在I形梁中产生应力波,用表面粘贴的光纤干涉仪来接收应力波产生的输出信号,对此信号进行频谱分析可找到I形梁的分层位置。理论分析和实验都表明了此方法探测复合材料梁腹板/翼缘连接处分层的可行性。

关键词： Mach—Zehnder光纤干涉仪分层复合材料腹板脉冲回波