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compressive strength, Pore size Distribution and chloride-ion Penetration of Recycled Aggregate concrete Incorporating class-F Fly Ash

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Journal of Wuhan University of Technology(Materials science) 2006年第4期21卷 130-136页

作者：寇世聪 c s poon Department of civil and structural Engineering The Hong Kong Polytechnic University Hung HomKowloon Hong Kong

The effects of fly ash on the compressive strength, pore size distribution and chloride-ion penetration of recycled aggregate concrete were investigated. Two series of concrete mb：tures were prepared. The concrete mixtures in series I had a water-to-binder ratio and a cement content of 0.55 and 410 kg/ m^3 , respectively. The concrete rnixtures in series II had a water-to-binder ratio and a cement content of 0.45 and 400 kg/ ml respectively. Recycled aggregate was ased as 20% , 50% , and 100% replacements of natural coarse aggregate in the concrete mixtures in both series. In cutdition, fly ash was used as 0% , 25% and 35% by weight replacements of cement. The results show that the compressive strengths of the concrete decreased as the recycled aggregate and the fly ash contents increased. The total porosity and average porosity diameter of the concrete increased us the recycled aggregate content increased. Furtherrruore , an increase in the recycled aggregate content decreased the resistance to chloride ion penetration. Nevertheless, the replacement of cement by 25% fly ush improved the resistance to chloride ion penetration and pore diameters and reduced the total porosity of the recycled aggregate concrete.

关键词： durability properties recycled aggregate concrete fly ash

Pore size Distribution of High Performance Metakaolin concrete

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Journal of Wuhan University of Technology(Materials science) 2002年第1期17卷 42-46页

作者： c.s.poon s.c.Kou L.Lam Department of civil and structural Engineering The Hong Kong Polytechnic University Hong Kong China

The compressive strength, porosity and pore size distribution of high performance metakaolin (MK) concrete were investigated. concretes containing 0,5% , 10% and 20% metakaolin were prepared at a water / cementitious material ratio ( W/c) of 0. 30. In parallel, concrete mixtures with the replacement of cement by 20% fly ash or 5 and 10% silica fume were prepared for comparison. The specimens were cured in water at 27℃ for 3 to 90 days. The results show that at the early age of curing (3 days and 7 days), metakaolin replacements increase the compressive strength, but silica fume replacement slightly reduces the compressive strength. At the age of and after 28 days , the compressive strength of the concrete with metakaolin and silica fume replacement increases. A strong reduction in the total porosity and average pore diameter were observed in the concrete with MK 20% and 10% in the first 7 days.

关键词： high performance concrete metakaolin pore size distribution

Use of Recycled Glass in Architectural Mortars

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武汉理工大学学报 2010年第17期32卷 231-234,245页

作者： poon c s LING T c B Department of civil and structural Engineering The Hong Kong Polytechnic UniversityHong KongChina

In recent years,recycled glass has been widely used as aggregate replacements in concrete. Owing to the aesthetic potential of the coloured recycled glass,this research aims to fully utilize this advantage for their higher end uses,such as architectural mortar. In this study,architectural white cement mortar was produced with a self consolidating method using recycled glass as the aggregate. An adequate amount of Metakaolin was incorporated into the mortar to mitigate the adverse effect of alkali-silica reaction. The results show that the self-compacting method is suitable to produce architectural mortar containing up to 100% recycled glass. Overall,the performance of all the architectural mortar mixtures in terms of both fresh and hardened properties was good.

关键词： recycled glass self-compacting architectural mortar AsR flexural strength

Do specific ultrasonography features identified at the time of early pregnancy loss predict fetal chromosomal abnormality? e A systematic review and meta-analysis

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Genes & Diseases 2019年第2期6卷 129-137页

作者： J.Huang W.Zhu J.Tang s.H.saravelos L.c.Y.poon T.c.Li Department of Obstetrics and Gynaecology The First Affiliated Hospital of Chongqing Medical UniversityChongqing400016China Department of Obstetrics and Gynaecology The Chinese University of Hong KongHong Kong SARChina IVF Unit Hammersmith HospitalImperial College Healthcare NHS TrustLondonUK

To investigate the association of specific ultrasonography features identified during the diagnosis of early pregnancy loss(EPL)and abnormal *** was a systematic review and meta-analysis conducted in accordance with PRIsMA *** searched PubMed,cochrane and Ovid MEDLINE from 1977 to Jan 2017 to identify the articles that described EPL with karyotype and ultrasonography *** differences were pooled to estimate the chromosomal abnormality rates in ultrasonography features,including pre-embryonic,enlarged yolk sac(Ys),short crown rump length(cRL),small gestational sac(Gs),symmetrical arrested growth embryo,or gestational sac with only a *** assessment of included studies was performed using strengthening the Reporting of Observational studies in Epidemiology(sTROBE)checklists for Observational studies(2007 version).Thirteen studies were included in the *** abnormality was more likely to occur in embryonic EPL and enlarged *** the other hand,short cRL,small Gs,symmetrical arrested growth embryo,or gestational sac with only a Ys,were not associated with an increased risk of fetal chromosomal *** features at the time of diagnosis of EPL have limited predictive value of fetal chromosomal abnormality.

关键词： Ultrasonography Early pregnancy loss chromosomal abnormality Predictive value

Recent studies on mechanical properties of recycled aggregate concrete in china-A review

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science china(Technological sciences) 2012年第6期55卷 1463-1480页

作者： XIAO JianZhuang LI WenGui poon chisun Department of Building Engineering Tongji UniversityShanghai 200092China Department of civil and structural Engineering Hong Kong Polytechnic UniversityHong KongChina committee of Recycled Aggregate concrete Civil Engineering SocietyShanghai 200092China

Numerous experimental and theoretical studies on recycled aggregate concrete have been carried out in china in the past 10 *** paper provides a comprehensive review of the related findings of research on the mechanical properties of RAc in *** influences of the RcA on the strength and deformation characteristics of concrete,the statistical characteristics for the strength of RAc,fracture energy,stress-strain relationships under uniaxial compression,uniaxial tension as well as pure shear,and the residual strength of RAc after exposure to high temperatures,the bond between RAc and different kinds of steel rebar were also ***,some recent studies on the numerical simulation of the failure mechanism for RAc at the meso-structure level were discussed.

关键词： construction and demolition (c&D) wastes recycled coarse aggregate (RcA) recycled aggregate concrete (RAc) me-chanical property test numerical simulation

The effect of downstream resistance on flow diverter treatment of a cerebral aneurysm at a bifurcation: A joint computational-experimental study

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Journal of Hydrodynamics 2018年第5期30卷 803-814页

作者： ANDerson c.O.Tsang Billy Y.s.Yiu Abraham Y.s.Tang W.c.chung Gilberto K.K.Leung AlexANDer K.K.poon Alfred c.H.Yu simon s.M.Lai K.W.chow Department of surgery Li Ka Shing Faculty of Medicine University of Hong Kong Department of Electrical and computer Engineering University of Waterloo Department of Mechanical Engineering University of Hong Kong Department of Electrical and Electronic Engineering University of Hong Kong

Intracranial aneurysm can lead to hemorrhagic stroke upon rupture. Deployment of flow diverters can restrict the blood flow into aneurysm and mitigate the rupture risk. computational fluid dynamics（cFD） and ultrasonography with pulse-wave and color Doppler ultrasound measurements were employed jointly to investigate the complex flow pattern in cerebral aneurysms, both before and after the deployment of flow diverters. Patient-specific configurations of both bifurcation and side-wall aneurysms were selected. The effect of downstream flow resistance was investigated by adjusting the volume flow rate and pressure at the outlet vessels computationally and experimentally. Velocity profiles in the aneurysm measured from ultrasonography showed good agreement with those from computer simulations. The discrepancy in velocity between the computational and experimental sets of data is less than 10%. The downstream resistance can alter the volume flux into a bifurcation aneurysm with a flow diverter deployed by 236%, while the corresponding value of a side-wall aneurysm is negligible. The vorticity of the aneurysmal flow was reduced by more than 80% in both cases after stenting. This study demonstrated that careful investigation of downstream flow resistance of a bifurcation aneurysm is essential to provide an accurate assessment of the aneurysmal flow dynamics after flow diverter deployment.

关键词： Intracranial aneurysms computational fluid dynamics (cFD) doppler ultrasound

The influence of moisture on the permeability of crushed shale samples

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Petroleum science 2019年第3期16卷 492-501页

作者： Mercy Achang jack c.Pashin Eliot A.Atekwana Boone Pickens school of Geology Oklahoma State UniversityStillwater OK 74078USA Department of Geological sciences University of DelawareNewarkDE 19716IJSA

shale cuttings and cores recovered from the subsurface and stored for hours to decades tend to dry out and lose moisture and hydrocarbons,leading to an increase in the effective matrix *** loss in shale samples is a fundamental sample preservation problem which can be solved by applying a standard moisture equilibration procedure to restore lost *** aim was to investigate the relationship between permeability and variable moisture as-received,as-received moisture-equilibrated and saturated moisture-equilibrated *** were crushed to a series of particle sizes(0.6-2.0)mm and moisture equilibrated at 97% relative *** show that moisture equilibration in the samples was achieved after 72 *** permeability of the saturated moisture-equilibrated and as-received moisture-equilibrated samples decreased exponentially with increase in moisture *** high correlation coefficient between permeability and particle size(r = 0.96 and 0.97)for moisture-equilibrated samples compared to 0.76 for as-received samples indicates that moisture equilibration improves permeability measurements in crushed shale ***,permeability measurements are repeatable for moisture-equilibrated samples compared to samples that were not equilibrated(as-received).We conclude that moisture content affects permeability and moisture equilibration normalizes and improves the repeatability of permeability measurements in crushed shale.

关键词： crushed shale Matrix permeability Moisture equilibration

Peroxyacetyl nitrate measurements by thermal dissociation-chemical ionization mass spectrometry in an urban environment： performance and characterizations

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Frontiers of Environmental science & Engineering 2017年第4期11卷 145-152页

作者： Xinfeng Wang Tao Wang Likun Xue Wei Nie Zheng Xu steven c. N. poon Wenxing Wang Environment Research Institute Shandong University Jinan 250100 China Department of civil and Environmental Engineering Hong Kong Polytechnic University Hong Kong 999077 China Institute for climate and Global change Research & school of Atmospheric sciences Nanjing University Nanjing 210023 China

Peroxyacetyl nitrate （PAN） is an important indicator of photochemical smog and has adverse effects on human health and vegetation growth. A rapid and h!ghly selective technique of thermal dissociation chemical ionization mass spectrometry （TD-cIMs） was recently developed to measure the abundance of PAN in real time; however, it may be subject to artifact in the presence of nitric oxide （NO）. In this study, we tested the interference of the PAN signal induced by NO, evaluated the performance of TD- cIMs in an urban environment, and investigated the concentration and formation of PAN in urban Hong Kong. NO caused a significant underestimation of the PAN signal in TD-cIMs, with the underestimation increasing sharply with NO concentration and decreasing slightly with PAN abundance. A formula was derived to link the loss of PAN signal with the concentrations of NO and PAN, which can be used for data correction in PAN measurements. The corrected PAN data from TD- cIMs were consistent with those from the commonly used gas chromatography with electron capture detection, which confirms the utility of TD-cIMs in an urban environment in which NO is abundant. In autumn of 2010, the hourly average PAN mixing ratio varied from 0.06 ppbv to 5.17 ppbv, indicating the occurrence of photochemical pollution in urban Hong Kong. The tbrmation efficiency of PAN during pollution episodes was as high as 3.9 to 5.9 ppbv per 100 ppbv ozone. The efficiency showed a near-linear increase with NO, concentration, suggesting a control policy of NO,. reduction for PAN pollution.

关键词： TD-cIMs Peroxyacetyl nitrate Interference Photochemical pollution Formation efficiency

Effects of DNA topoisomerase IIα splice variants on acquired drug resistance

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cancer Drug Resistance 2020年第2期3卷 161-170页

作者： Terry s.Elton Hatice Gulcin Ozer jack c.Yalowich Division of Pharmaceutics and Pharmacology College of PharmacyThe Ohio State UniversityColumbusOH 43210USA Department of Biomedical Informatics College of MedicineThe Ohio State UniversityColumbusOH 43210USA

DNA topoisomerase IIα(170 kDa,TOP2α/170)induces transient DNA double-strand breaks in proliferating cells to resolve DNA topological entanglements during chromosome condensation,replication,and ***,TOP2α/170 is a prominent target for anticancer drugs whose clinical efficacy is often compromised due to *** many resistance mechanisms have been defined,acquired resistance of human cancer cell lines to TOP2αinterfacial inhibitors/poisons is frequently associated with a reduction of Top2α/170 expression *** studies by our laboratory,in conjunction with earlier findings by other investigators,support the hypothesis that a major mechanism of acquired resistance to TOP2α-targeted drugs is due to alternative RNA processing/***,several TOP2αmRNA splice variants have been reported which retain introns and are translated into truncated TOP2αisoforms lacking nuclear localization sequences and subsequent dysregulated nuclear-cytoplasmic *** addition,intron retention can lead to truncated isoforms that lack both nuclear localization sequences and the active site tyrosine(Tyr805)necessary for forming enzyme-DNA covalent complexes and inducing DNA damage in the presence of TOP2α-targeted ***,these truncated TOP2αisoforms result in decreased drug activity against TOP2αin the nucleus and manifest drug ***,the complete characterization of the mechanism(s)regulating the alternative RNA processing of TOP2αpre-mRNA may result in new strategies to circumvent acquired drug ***,novel TOP2αsplice variants and truncated TOP2αisoforms may be useful as biomarkers for drug resistance,prognosis,and/or direct future TOP2α-targeted therapies.

关键词： DNA topoisomerase IIα chemoresistance alternative splicing intron retention topoisomerase IIαinterfacial inhibitors/poisons