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Catalytically active interfaces in titania nanorod-supported copper catalysts for CO oxidation

Nano Research 2020年第2期13卷 533-542页

作者： wasim U.Khan Season S.Chen Daniel C.w.Tsang wey yang Teoh Xijun Hu Frank L.y.lam Alex C.K.yip Department of Chemical and Process Engineering The University of Canterbury Christchurch 8041New Zealand Department of Civil and Environmental Engineering.The Hong Kong Polytechnic University Hong Kong.China School of Chemical Engineering The University of New South WalesSydneyNSW 2052Australia Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyHong KongChina

One-dimensional titanium dioxide nanorod(TNR)-supported Cu catalysts(2.5 wt.%-12.5 wt.%)were synthesized using deposition-precipitation.X-ray photoelectron spectroscopy,temperature programmed reduction and CO chemisorption measurements showed that Cu doping over TNR offered metal-support interactions and interfacial active sites that had a profound impact on the catalytic *** role of the Cu-TNR interface was investigated by comparing the catalytic activity of Cu-TNR catalysts with that of pure CuO nanoparticles in CO *** presence of highly dispersed copper species,a high number of interfacial active sites,CO adsorption capacity and surface/lattice oxygen were found to be responsible for the excellent activity of 7.5CU-TNR(ie,Cu loading of 7.5 wt.%on TNR).Moreover,the Cu-TNR catalysts followed the Langmuir-Hinshelwood reaction mechanism with 7.5CU-TNR,exhibiting an apparent activation energy of 44.7 kJ/*** TNR-supported Cu catalyst gave the highest interfacial catalytic activity in medium-temperature CO oxidation(120-240℃)compared to other commonly used supports,including titanium dioxide nanoparticles(TiO2-P25),silica(SiO2)and alumina(Al20g)in which copper species were nonhomogeneously *** study confirms that medium-temperature CO oxidation is highly sensitive to the morphology and structure of the supporting material.

关键词： supported catalysts nanorod oxygen species interfacial active sites CO oxidation

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Role of the forkhead transcription factor FOXO-FOXM1 axis in cancer and drug resistance

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Frontiers of Medicine 2012年第4期6卷 376-380页

作者： Fung Zhao Eric w.-F.lam Department of Surgery and Cancer Imperial College LondonHammersmith Hospital CampusLondon W120NNUK

The forkhead transcription factors FOXO and FOXM1 have pivotal roles in tumorigenesis and in mediating chemotherapy sensitivity and *** research shows that the forkhead transcription factor FOXM1 is a direct transcriptional target repressed by the forkhead protein FOXO3a,a vital downstream effector of the PI3K-AKT-FOXO signaling ***,FOXM1 and FOXO3a also compete for binding to the same gene targets,which have a role in chemotherapeutic drug action and *** understanding of the role and regulation of the FOXO-FOXM1 axis will impact directly on our knowledge of chemotherapeutic drug action and resistance in patients,and provide new insights into the design of novel therapeutic strategy and reliable biomarkers for prediction of drug sensitivity.

关键词： FOXO3a FOXM1 transcription factor cancer drug resistance tumorigenesis

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Vibration analysis of hard-coated composite beam considering the strain dependent characteristic of coating material

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Acta Mechanica Sinica 2016年第4期32卷 731-742页

作者： w.Sun y.Liu School of Mechanical Engineering and Automation Northeastern University State Key Laboratory of Mechanical System and Vibration Institute of Vibration Shock and Noise Shanghai Jiao Tong University

The strain dependent characteristics of hard coatings make the vibration analysis of hard-coated composite structure become a challenging task. In this study, the modeling and the analysis method of a hard-coated composite beam was developed considering the strain dependent characteristics of coating material. Firstly, based on analyzing the properties of hard-coating material, a high order polynomial was adopted to characterize the strain dependent characteristics of coating materials. Then, the analytical model of a hard-coated composite beam was created by the energy method. Next, using the numerical method to solve the vibration response and the resonance frequencies of the composite beam, a specific calculation flow was also proposed. Finally,a cantilever beam coated with Mg O ＋ Al2_O_3 hard coating was chosen as the study case; under different excitation levels, the resonance region responses and the resonance frequencies of the composite beam were calculated using the proposed method. The calculation results were compared with the experiment and the linear calculation, and the correctness of the created model was verified. The study shows that compared with the general linear calculation, the proposed method can still maintain an acceptable precision when the excitation level is larger.

关键词： coated excitation modulus verified challenging characterize created considering acceptable polynomial

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Phase change memory

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Science China(Information Sciences) 2011年第5期54卷 1061-1072页

作者： lam Chung IBM Research T.J. Watson Research Center Yorktown Heights New York 10598 USA

Phase change memory (PCM) is a non-volatile solid-state memory technology based on the large resistivity contrast between the amorphous and crystalline states in phase change materials. we present the physics behind this large resistivity contrast and describe how it is being exploited to create high density PCM. we address the challenges facing this technology, including the design of PCM cells, fabrication, device variability, thermal cross-talk and write disturb. we discuss the scalability, assess the performance, and examine the reliability of PCM including data retention, multi-bit storage and endurance.

关键词： solid state memory non-volatile DRAM flash phase change resistive memory data retention write endurance solid-state drive computer memory

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Towards creep property improvement of selective laser melted Ni-based superalloy IN738LC

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Journal of Materials Science & Technology 2022年第17期112卷 301-314页

作者： H.y.Song M.C.lam y.Chen S.wu P.D.Hodgson X.H.wu y.M.Zhu A.J.Huang Monash Centre for Additive Manufacturing 15-17 Normanby RdNotting HillVIC 3168Australia Department for of Materials Science and Engineering Monash UniversityClaytonVIC 3800Australia Monash Centre for Electron Microscopy 10 Innovation WalkClaytonVIC 3800Australia Institute for Frontier Materials Deakin UniversityVIC 3216Australia

Nickel-based superalloy IN738LC produced by selective laser melting(SLM)exhibits inferior hightemperature creep properties than its cast counterparts due to relatively smaller grain size,particularly for the plane normal to the building *** work studied effects of post heating strategy on the microstructure and especially the grain size to improve the high temperature creep *** asbuilt microstructure exhibited a fine grain size and large quantities of MC carbides that could effectively hinder grain *** was found that unconventional two-step heat treatments could lead to substantial grain growth,and the effect is particularly prominent at a specific *** ease of grain growth was explained after classifying the microstructural evolution(boundary carbide transformation)during each heating step and related to the reduced grain boundary pinning force from MC *** tests validated the effect of the new heat treatment scheme on the SLM-processed IN738LC at 850℃.An extended creep fracture life(1.5 to 4 times improvement)and lower secondary creep rates were achieved with samples subjected to the newly optimized two-step heat *** complete creep curves are also firstly presented for SLM-IN738LC,confirming the effectiveness of grain growth and highlighting the importance of dedicated heat treatment for SLM superalloys.

关键词： Selective laser melting IN738LC alloy Creep properties Heat treatments Grain structure

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Spray freeze drying of small nucleic acids as inhaled powder for pulmonary delivery

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Asian Journal of Pharmaceutical Sciences 2018年第2期13卷 163-172页

作者： wanling Liang Alan y.L.Chan Michael y.T.Chow Fiona F.K.Lo yingshan Qiu Philip C.L.Kwok Jenny K.w.lam Department of Pharmacology and Pharmacy Li Ka Shing Faculty of Medicine The University of Hong Kong Advanced Drug Delivery Group Faculty of Pharmacy The University of Sydney

The therapeutic potential of small nucleic acids such as small interfering RNA(siRNA) to treat lung diseases has been successfully demonstrated in many in vivo studies. A major barrier to their clinical application is the lack of a safe and efficient inhaled *** this study, spray freeze drying was employed to prepare dry powder of small nucleic *** and herring sperm DNA were used as bulking agent and model of small nucleic acid therapeutics, respectively. Formulations containing different solute concentration and DNA concentration were produced. The scanning electron microscope(SEM) images showed that the porosity of the particles increased as the solute concentration decreased. Powders prepared with solute concentration of 5% w/v were found to maintain a balance between porosity and robustness. Increasing concentration of DNA improved the aerosol performance of the formulation. The dry powder formulation containing 2% w/w DNA had a median diameter of 12.5 μm, and the aerosol performance study using next generation impactor(NGI) showed an emitted fraction(EF) and fine particle fraction(FPF) of 91% and 28% respectively. This formulation(5% w/v solute concentration and 2% w/w nucleic acid) was adopted subsequently to produce siRNA powder. The gel retardation and liquid chromatography assays showed that the siRNA remained intact after spray freeze drying even in the absence of delivery vector. The siRNA powder formulation exhibited a high EF of 92.4%and a modest FPF of around 20%. Further exploration of this technology to optimise inhaled siRNA powder formulation is warranted.

关键词： Inhalation Pulmonary delivery Small interfering RNA Spray freeze drying

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Chemical characteristics of aerosols at coastal station in Hong Kong.Ⅱ. Environmental behavior of trace elements during the April 1995 to April 1996

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Journal of Environmental Sciences 2004年第2期16卷 212-221页

作者： K.S.lam Z.L.Cheng S.C.Kot C.w.Tsang Department of Civil and Structural Engineering the Hong Kong Polytechnic UniversityResearch Center for Eco-Environmental Sciences Chinese Academy of SciencesDepartment of Mechanical Engineering The Hong Kong University of Science & Technology Clear Water BayDepartment of Applied Biology and Chemical Technology the Hong Kong Polytechnic University Hung Hom Hong Kong ChinaBeijing 100085 ChinaHong Kong ChinaHung Hom Hong Kong China

An one-year of sampling aerosol program was carried out during the period of April 1995 to April 1996 at coastal region, Cape D′Aguilar, in Hong Kong. The trace element composition of aerosol particles(TSP and PM 10 ) were measured and analyzed by using the Instrumental Neutron Activation Analysis(INAA) and Inductive Couple Plasma-Mass Spectrometry(ICP-MS) techniques. The results showed that the polluted elements such as: V, Zn, As, Pb, Cd, Sb, I, Se, Bi, with high enrichment factor(E.F) values, are derived from anthropogenic sources, while Sc, Al, Fe, Mn, Sm, La, Sr are less than 10 in E.F, these elements are related the crust and soil. The concentration of the trace elements are present seasonal variation i.e. summer low and winter high, whereas the V or noncrustal V(V *) present summer high and winter low, this phenomenon might be explained by local or regional oil combustion sources. Use three type of elemental ratio, e.g. La/Sm, Mn */V * and Bi/Al indicate that both TSP and PM 10 of La/Sm ratios are mainly related to soil and dust, Mn */V * are probably represent fossil combustion and Bi/Al are possibly associated with refuse incineration, ferromanganese alloys and aluminum production. The varimax rotation factor analysis for trace elements was performed. By means of the absolute principal component analysis(APCA) and multiple regression, the contribution of trace elements to possible sources and overall means of trace elements were estimated. The results showed that the present station is impacted by the anthropogenic species, although the quantities are different during the summertime and wintertime.

关键词： TSP PM 10 trace elements enhancement factor element ratios seasonal variation factor analysis

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MECHANICAL PROPERTIES OF Ti_3SiC_2 AT HIGH TEMPERATURE

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 465-470页

作者： y.w.Bao y.C.Zhou Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 ChinaShenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Creep and stress relaxation behavior, the elastic modulus and fracture toughness of machinable Ti3SiC2 at various temperatures from 20 to 1250℃ were investigated by means of three-point bending tests. The experiments were performed respectively at: (i) fixed stress and changed temperatures, and (ii) fixed temperature and changed stresses. A creep resistance parameter that represents the probability of creep deformation in a given condition was defined as a function of both applied stress and the threshold stress, varying in a range from 0 to 1. Elastic modulus at high temperatures was measured through comparing relative slopes of loading curves in cyclic loading curve. The fracture toughness measured by SENB method showed a stable value in the range of 25-1000℃, but over 1000℃, it declined abruptly from -6.7MPa·m1/2 to -2.0MPa·m1/2 at 1200℃.

关键词： high-temperature Ti3SiC2 creep stress relaxation fracture toughness

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被分析物在微流体器件中的分散特性

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机械工程学报 2006年第3期42卷 93-98页

作者：赵志文陈兴 lam y C 北京师范大学电子学系北京100875 新加坡-MIT联盟新加坡南洋理工大学机械与航空航天学院新加坡639798

与电场驱动方式相比,采用压力驱动方式实现对微流体的控制,具有简单方便和适应性广等特点,但微流体的流动特性也更为复杂。在分析研究微流体一被分析物在流场中分散机理的基础上,针对具有窄缝形状的y型微流体器件中两种同物性流体的流... 详细信息

与电场驱动方式相比,采用压力驱动方式实现对微流体的控制,具有简单方便和适应性广等特点,但微流体的流动特性也更为复杂。在分析研究微流体一被分析物在流场中分散机理的基础上,针对具有窄缝形状的y型微流体器件中两种同物性流体的流动特性,采用平均分析法,对微型矩形窄缝中的压力流的传质现象进行了初步研究,提出二维分析模型,并导出了其分析解。

关键词：扩散/对流传质微流体器件压力定常流泰勒分散

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Frequency Veering of Rotating Metal Porous Twisted Plate with Cantilever Boundary Using Shell Theory

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Acta Mechanica Solida Sinica 2022年第2期35卷 282-302页

作者： y.y.Liu y.X.Hao w.Zhang L.T.Liu S.w.yang y.T.Cao College of Mechanical Engineering Beijing Information Science and Technology UniversityBeijing 100192China College of Mechanical Engineering Beijing University of TechnologyBeijing 100124China

The frequency veering of a metal porous rotating cantilever twisted plate with twist angle and stagger angle is *** porous materials may have the characteristics of gradient or uniform distribution along the thickness *** on the classical shell theory,considering the influence of centrifugal force produced by high-speed rotation,the free vibration equations of a rotating cantilever twisted plate are *** the polynomial function and Rayleigh-Ritz method,the natural frequencies and mode shapes of the metal porous cantilever twisted plate in both static and rotating states are *** accuracy of the present theory and calculation results is confirmed by a comparison between them and the results available from the literature and those obtained from *** influences of the thickness ratio,porosity,twist angle,stagger angle and rotational velocity on the frequency veering and mode shape shift of the rotating cantilever twisted plate with porous material under three different distributions are *** should be mentioned that the frequency veering accompanied by mode shape shift occurs in both static and dynamic states.

关键词： Frequency veering Rotating twisted plate Cantilever boundary Metal porous

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