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Energy transfer and luminescent properties of Tb^(3+)and Tb^(3+),Yb^(3+)doped CNGG phosphors

Journal of Rare Earths 2022年第9期40卷 1445-1453,I0004页

作者： s.hau G.stanciu D.Avram L.Gheorghe C.Gheorghe National Institute for Laser Plasma and Radiation PhysicsSolid State Quantum Electronics Laboratory409 Atomistilor StreetP.O.Box MG-36Magurele077125IlfovRomania

In this work,calcium niobium gallium garnet(Ca_(3)Nb_(1.6875)Ga_(3.1875)O_(12)-CNGG)ceramic samples singledoped with Tb^(3+)and co-doped with Tb^(3+)and Yb^(3+)ions were sintered by the solid-state reaction *** structural characterization of the samples was carried out by X-ray diffraction *** optimal concentration of Tb^(3+)ions corresponding to the maximum luminescence in the green spectral range in CNGG:x at%Tb(x=0.1,0.5,1,2,3,4,and 5)was determined to be 4 at%.The timeresolved luminescence of the^(5)D_(4)level(Tb^(3+))in the CNGG:x at%Tb samples was analysed to explore the quenching mechanisms involved in the Tb^(3+)green ***-doped CNGG:4 at%Tb,y at%Yb(y=0.5,2,4,6,8,and 10)ceramics were prepared and *** is shown that CNGG:4 at%Tb,y at%Yb phosphors exhibit intense green luminescence under ultra-violet(UV),visible(VIs),and near-infrared(NIR)excitation,thus demonstrating the presence of simultaneous down-conversion(DC)and upconversion(UC)*** dependence of the UC luminescence intensity on the diode laser pumping power was measured and the results indicate a two-photon process based on cooperative energy transfer(CET).Under UV excitation,the lifetime of the^(5)D_(4)(Tb^(3+))level slowly increases with increase of Yb^(3+)concentration,suggesting the energy transfer from Yb^(3+)to Tb^(3+)ions,while under NIR excitation,the lifetime of the^(5)D_(4)(Tb^(3+))level decreases with increase of Yb^(3+)ions concentration,indicating the presence of a strong energy transfer from Tb^(3+)to Yb^(3+)*** highest energy transfer efficiency ofη_(ET)≈42%was determined for the CNGG:4 at%Tb,10 at%Yb *** obtained results indicate that CNGG:(Tb^(3+),Yb^(3+))could be efficient new yellowish-green-emitting phosphors.

关键词： Phosphors Tb^(3+)and Tb^(3+)-Yb^(3+)luminescence properties Up-conversion Down-conversion Quantum cutting process Rare earths

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Interplay of laser power and pore characteristics in selective laser melting of ZK60 magnesium alloys:A study based on in-situ monitoring and image analysis

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Journal of Magnesium and Alloys 2024年第4期12卷 1346-1366页

作者： Weijie Xie hau-Chung Man Chi-Wai Chan Department of Industrial and systems Engineering The Hong Kong Polytechnic UniversityHong KongChina school of Mechanical and Aerospace Engineering Queen’s UniversityBelfast BT95AHUK Research Institute for Advanced Manufacturing The Hong Kong Polytechnic UniversityHong KongChina

This study offers significant insights into the multi-physics phenomena of the sLM process and the subsequent porosity characteristics of ZK60 Magnesium(Mg)***-speed in-situ monitoring was employed to visualise process signals in real-time,elucidating the dynamics of melt pools and vapour plumes under varying laser power conditions specifically between 40 W and 60 *** morphological analysis was performed using scanning-Electron Microscopy(sEM),demonstrating a critical correlation between laser power and pore *** laser power led to increased pore coverage,whereas a denser structure was observed at higher laser *** laser power influence on porosity was further confirmed via Optical Microscopy(OM)conducted on both top and cross-sectional surfaces of the *** increase in laser power resulted in a decrease in pore coverage and pore size,potentially leading to a denser printed part of Mg alloy.X-ray Computed Tomography(XCT)augmented these findings by providing a 3D volumetric representation of the sample internal structure,revealing an inverse relationship between laser power and overall pore *** laser power appeared to favour the formation of interconnected pores,while a reduction in interconnected pores and an increase in isolated pores were observed at higher *** interplay between melt pool size,vapour plume effects,and laser power was found to significantly influence the resulting porosity,indicating a need for effective management of these factors to optimise the sLM process of Mg alloys.

关键词： selective laser melting(sLM) Magnesium(Mg)alloys Biodegradable implants Porosity In-situ monitoring

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Learning about good nutrition with the 5-color front-of-package label"Nutri-score":an experimental study

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Food science and Human Wellness 2024年第3期13卷 1195-1200页

作者： Robin C.hau Klaus W.Lange University of Applied sciences Landshut Landshut 84036Germany Faculty of Human sciences University of RegensburgRegensburg 93040Germany

The Nutri-score is a 5-color front-of-pack nutrition label designed to provide consumers with an easily understandable guideline to the healthiness of food *** impact that the Nutri-score may have on consumers'choices is unclear since different experimental paradigms have found vastly different effect *** the present study,we have investigated how student participants change a hypothetical personal 1-daydietary plan after a learning phase during which they learn about the Nutri-scores of the available food *** were instructed to compose a healthy diet plan in order that the question of whether the Nutriscore would improve their ability to compose a healthy dietary plan could be investigated,independent of the question of whether they would apply this knowledge in their ordinary *** found a substantial(Cohen's d=0.86)positive impact on nutritional quality(as measured by the Nutrient Profiling system score of the Food standards Agency)and a medium-sized(Cohen's d=0.43)reduction of energy *** content reduction was larger for participants who had initially composed plans with higher energy *** results suggest that the Nutri-score has the potential to guide consumers to healthier food *** remains unclear,however,whether this potential will be reflected in real-life dietary choices.

关键词： Nutri-score Front-of-package label Nudge Nutrition Health

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Electrolyte Effect on Photoetching of Gallium Nitride

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Nanomanufacturing and Metrology 2024年第1期7卷 61-74页

作者： Huiqiang Liang Zhenghao Wei Jiongchong Fang Yanming Li Changli Li Zhirun Xie Yun hau Ng Guosong Zeng shenzhen Key Laboratory of Intelligent Robotics and Flexible Manufacturing systems Southern University of Science and TechnologyShenzhen 518055People’s Republic of China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055People’s Republic of China school of Materials Sun Yat-Sen UniversityGuangzhou 510275People’s Republic of China school of Energy and Environment City University of Hong KongKowloon 999077Hong Kong SARPeople’s Republic of China City University of Hong Kong shenzhen Research Institute Shenzhen Hi-Tech Industrial ParkNanshan DistrictShenzhen 518000People’s Republic of China sUsTech Energy Institute for Carbon Neutrality Southern University of Science and TechnologyShenzhen 518055People’s Republic of China

The limited material removal rate of conventional chemical mechanical polishing(CMP)significantly hinders the fabrica-tion efficiency and surface quality,thereby preventing the development of gallium nitride(GaN)-based ***,the incorporation of photoelectrochemistry in CMP has garnered increasing attention because of its potential to enhance the quality and efficiency of the GaN ***,a considerable gap still exists in the comprehensive understanding of the specific photoelectrochemical(PEC)behavior of ***,we report the influence of the electrolyte on the PEC etching of *** acids and bases were tested,with their pH being carefully *** concentrations of the cations and anions were also *** results showed that photocorrosion/photoetching was more pronounced in sulfuric acid,phosphoric acid,and nitric acid environments than in alkaline environments,but it was less pronounced in hydrochloric ***,the effects of pH and anion concentration on photoetching were investigated,and the results revealed that pho-toetching in acidic environments weakened with increasing pH levels and diminished with increasing sulfate *** underlying reasons contributing to this observation were *** findings provide ideas for improving the pho-toetching efficiency of GaN,thereby enriching the photoelectrochemical mechanical polishing(PECMP)technology of GaN.

关键词： GaN Photoelectrochemistry Photoetching pH

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An Easily Operating Polymer 1×4 Optical Waveguide switch Matrix Based on Vertical Couplers

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Chinese Physics Letters 2007年第6期24卷 1728-1730页

作者： Kaixin Chen Pak L Chu hau Ping Chan Kin s. Chiang Department of Electronic Engineering City University of Hong Kong Kowloon Hong Kong Cotco Holdings Ltd Science Park Hong Kong

A three-dimensional （3D） polymer thermo-optic （TO） 1 × 4 waveguide switch matrix based on vertical couplers is demonstrated. It consists of four basic 3D switch units and because of its 3D structure, its construction is compact, only 9 mm in length; moreover, the control logic of the entire switch is very simple, the light signal can be easily switched to any output port by operating only a single switch unit. The finished devices exhibit a switching extinction ratio greater than 21 dB for all of four output ports and the crosstalk between two adjacent output ports is lower than -19 dB. The rise time and the fall time of the switch matrix are 0.8ms and 1.4ms, respectively. The required electrical power to initiate the switching function for M1 switching units is about 50mW.

关键词： Operating Waveguide Vertical

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重建可持续未来——相互理解如何强化建筑对2030年议程的贡献

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世界建筑 2024年第1期 10-13页

作者：英格博格·豪孙斯坦(译) 丹麦皇家建筑艺术学院建筑与技术研究所

将6000名从事可持续建筑工作的专业人士聚集到哥本哈根是一项不小的投入。这不仅需要大量时间来策划,还要求每位参与者投入时间、精力和财力,更不用说整个项目所带来的巨大碳足迹。当大会的主题是“2030年议程”和“联合国17项可持续发... 详细信息

将6000名从事可持续建筑工作的专业人士聚集到哥本哈根是一项不小的投入。这不仅需要大量时间来策划,还要求每位参与者投入时间、精力和财力,更不用说整个项目所带来的巨大碳足迹。当大会的主题是“2030年议程”和“联合国17项可持续发展目标”,并且题目为“可持续未来——不让任何一个人掉队”时,这或许显得有些自相矛盾。在世界上最昂贵的城市之一举办这样一场资源密集型的盛会,如何促进可持续发展呢?

关键词：资源密集型可持续发展目标可持续未来可持续建筑哥本哈根碳足迹相互理解专业人士

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Numerical simulation of Moving Contact Lines with surfactant by Immersed Boundary Method

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Communications in Computational Physics 2010年第9期8卷 735-757页

作者： Ming-Chih Lai Yu-hau Tseng Huaxiong Huang Center of Mathematical Modeling and scientific Computing Department of Applied Mathematics National Chiao Tung University1001Ta Hsueh RoadHsinchu 300Taiwan Department of Mathematics and statistics York UniversityTorontoOntarioM3J 1P3Canada

In this paper,we present an immersed boundary method for simulating moving contact lines with *** governing equations are the incompressible Navier-stokes equations with the usual mixture of Eulerian fluid variables and Lagrangian interfacial *** immersed boundary force has two components:one from the nonhomogeneous surface tension determined by the distribution of surfactant along the fluid interface,and the other from unbalanced Young’s force at the moving contact *** artificial tangential velocity has been added to the Lagrangian markers to ensure that the markers are uniformly distributed at all *** corresponding modified surfactant equation is solved in a way such that the total surfactant mass is *** experiments including convergence analysis are carefully *** effect of the surfactant on the motion of hydrophilic and hydrophobic drops are investigated in detail.

关键词： Immersed boundary method interfacial flow Navier-stokes equations surfactant moving contact line hydrophilic drop hydrophobic drop wetting

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Impact of Renewable Energy sources on steady-state stability of Weak AC/DC systems

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CsEE Journal of Power and Energy systems 2017年第4期3卷 419-430页

作者： Denis Lee hau Aik Göran Andersson sarawak Electricity supply Corporation SarawakMalaysia swiss Federal Institute of Technology ETHZürichSwitzerland

In recent years,the penetration of renewable resources into AC power systems has increased tremendously,creating a significantly impact on the latter’s operations and *** this respect,it is also important to gain a basic analytical understanding of such impact on the steady-state stability of power systems with electrically weak AC/DC interconnections,but such works are not very evident in the ***,a classical analytic model of the single and multi-infeed HVDC system which now incorporates renewable resources is *** the well-established concept of voltage sensitivity of the AC/DC interconnection is applied to analyze the impact of the renewable resources on the steady-state stability of these composite system models,as well as on the influence of system conditions and *** impact is also compared with that arising from other types of shunt devices alternatively connected at the same AC/DC interconnection,therefore their relative beneficial or negative impacts will also be benchmarked.

关键词： single and multi-infeed HVDC system model incorporating renewable sources steady-state stability voltage sensitivity method weak AC/DC interconnection

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Macrocyclic-ligand Induced synthesis of Aryl Ethynides with Divergent silver（I） Clusters

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Chinese Journal of Chemistry 2017年第12期35卷 1824-1828页

作者： Guangmian Ji siqi Zhang sam C. K. hau Liang Zhao The Key Laboratory ofBioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education) Department of Chemistry Tsinghua University Beijing 100084 China Department of Chemistry Hong Kong Baptist University Kowloon Hong Kong SAR China

Two structurally characterized metal-cluster-centered supramolecular architectures named [Ag8（1,2-（C= C）2-C6H4）（Py[6]）（CF3CO2）6]·2.5MeOH （1） and [Ag12（1,2,4,5-（C=C）aC6H2）（Py[6]）2（CF3sO3）s]·4MeOH·3H2O （2） are synthesized through the interaction with a bowl-shaped macrocyclic ligand PyI61. Particularly, two dissimilar silver（I） clusters are resulted in 2 within the structure under the influence of the macrocyclic ligand Py[6]. such dissimilarity of the silver（1） cluster is also reflected on the structural and photophysical differences between 1 and 2.

关键词： macrocycle silver ethynide silver clusters dissimilarity supramolecular architecture

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A flexible capacitive photoreceptor for the biomimetic retina

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Light(science & Applications) 2022年第1期11卷 38-49页

作者： Mani Teja Vijjapu Mohammed E.Fouda Agamyrat Agambayev Chun Hong Kang Chun-Ho Lin Boon s.Ooi Jr-hau He Ahmed M.Eltawil Khaled N.salama sensors lab Advanced Membranes and Porous Materials CenterComputerElectrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Communication and Computing systems Lab ComputerElectrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Department of Electrical Engineering and Computer science University of California-IrvineIrvineCA 92612USA Department of Electrical Computer and Energy EngineeringArizona State UniversityTempeAZUSA Computer Electrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Department of Materials science and Engineering City University of Hong KongHong Kong SARChina

Neuromorphic vision sensors have been extremely beneficial in developing energy-efficient intelligent systems for robotics and privacy-preserving security *** is a dire need for devices to mimic the retina's photoreceptors that encode the light illumination into a sequence of spikes to develop such ***,we develop a hybrid perovskite-based flexible photoreceptor whose capacitance changes proportionally to the light intensity mimicking the retina's rod cells,paving the way for developing an efficient artificial retina *** proposed device constitutes a hybrid nanocomposite of perovskites(methyl-ammonium lead bromide)and the ferroelectric terpolymer(polyvinylidene fluoride trifluoroethylene-chlorofluoroethylene).A metal-insulator-metal type capacitor with the prepared composite exhibits the unique and photosensitive capacitive behavior at various light intensities in the visible light *** proposed photoreceptor mimics the spectral sensitivity curve of human photopic *** hybrid nanocomposite is stable in ambient air for 129 weeks,with no observable degradation of the composite due to the encapsulation of hybrid perovskites in the hydrophobic *** functionality of the proposed photoreceptor to recognize handwritten digits(MNIsT)dataset using an unsupervised trained spiking neural network with 72.05%recognition accuracy is *** demonstration proves the potential of the proposed sensor for neuromorphic vision applications.

关键词： perovskite illumination preserving

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